Detection device, electronic apparatus, detection method and program

ABSTRACT

A detection device that detects an operation by a user on a display in midair, includes: a control unit that changes a positional relationship between a detection reference detecting the operation and the display, wherein: the control unit is capable of changing the positional relationship by user.

TECHNICAL FIELD

The present invention relates to a detection device, an electronicapparatus, a detection method and a program.

BACKGROUND ART

There is an electronic device disclosed in the related art, which iscapable of detecting an operation performed on a three-dimensionalobject displayed in midair via a capacitive touch sensor that calculatesthe distance between a finger and a touch panel (see PTL 1).

CITATION LIST Patent Literature

PTL 1: Japanese Laid Open Patent Publication No. 2012-203737

SUMMARY OF INVENTION Technical Problem

While PTL 1 describes detecting an operation performed on athree-dimensional object (target), operability of operations performedon the object is not assured in the art disclosed in PTL 1.

According to the 1st aspect of the present invention, a detection devicethat detects an operation by a user on a display in midair comprises: acontrol unit that changes a positional relationship between a detectionreference detecting the operation and the display, wherein: the controlunit is capable of changing the positional relationship by user.

According to the 2nd aspect of the present invention, a detection devicethat detects an operation by a user on a display in midair, comprises: acontrol unit that changes a positional relationship between a detectionreference detecting the operation and the display based on informationrelating to the user.

According to the 3rd aspect of the present invention, a detection devicethat detects an operation performed on a display in midair, comprises: acontrol unit that changes a positional relationship between a detectionreference detecting the operation and the display based on theoperation.

According to the 4th aspect of the present invention, a detection devicecomprises: a detection unit that detects an operation by a user on adisplay in midair and changes a positional relationship between adetection reference detecting the operation and the display, wherein:the detection unit is capable of changing the positional relationship byuser.

According to the 5th aspect of the present invention, a detection devicecomprises: a detection unit that detects an operation by a user on adisplay in midair and changes a positional relationship between adetection reference detecting the operation and the display based oninformation on the user.

According to the 6th aspect of the present invention, a detection devicecomprises: a detection unit that detects an operation performed on adisplay in midair and changes a positional relationship between adetection reference detecting the operation and the display based on theoperation.

According to the 7th aspect of the present invention, a detection methodfor detecting an operation by a user on a display in midair comprises:changing a positional relationship between a detection referencedetecting the operation and the display by user.

According to the 8th aspect of the present invention, a detection methodfor detecting an operation by a user on a display in midair comprises:changing a positional relationship between a detection referencedetecting the operation and the display based on information on theuser.

According to the 9th aspect of the present invention, a detection methodfor detecting an operation performed on a display in midair comprises:changing a positional relationship between a detection referencedetecting the operation and the display based on the operation.

According to the 10th aspect of the present invention, a detectionmethod, comprises: detecting an operation performed by a user on adisplay in midair; and changing a positional relationship between adetection reference detecting the operation and the display by user.

According to the 11th aspect of the present invention, a detectionmethod comprises: detecting an operation by a user on a display inmidair; and changing a positional relationship between a detectionreference detecting the operation and the display based on informationon the user.

According to the 12th aspect of the present invention, a detectionmethod comprises: detecting an operation performed on a display inmidair; and changing a positional relationship between a detectionreference detecting the operation and the display based on theoperation.

According to the 13th aspect of the present invention, a program thatenables a computer to execute detection of an operation by a user on adisplay in midair comprises: processing for changing a positionalrelationship between a detection reference detecting the operation andthe display by user.

According to the 14th aspect of the present invention, a program thatenables a computer to execute detection of an operation by a user on adisplay in midair comprises: processing for changing a positionalrelationship between a detection reference detecting the operation andthe display based on information on the user.

According to the 15th aspect of the present invention, a program thatenables a computer to execute detection of an operation performed on adisplay in midair comprises: processing for changing a positionalrelationship between a detection reference detecting the operation andthe display based on the operation.

According to the 16th aspect of the present invention, a program thatenables a computer to execute comprises: processing for detecting anoperation performed by a user on a display in midair; and processing forchanging a positional relationship between a detection referencedetecting the operation and the display by user.

According to the 17th aspect of the present invention, a program thatenables a computer to execute comprises: processing for detecting anoperation by a user on a display in midair; and processing for changinga positional relationship between a detection reference detecting theoperation and the display based on information on the user.

According to the 18th aspect of the present invention, a program thatenables a computer to execute comprises: processing for detecting anoperation performed on a display in midair; and processing for changinga positional relationship between a detection reference detecting theoperation and the display based on the operation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 The structure of the display device achieved in a firstembodiment, illustrated in a disassembled oblique view in (a) and in asectional view in (b)

FIG. 2 A block diagram showing the main configuration of the displaydevice achieved in the first embodiment

FIG. 3 A schematic presentation of a midair image displayed in the firstembodiment in a plan view in (a) and in sectional views, each indicatingthe relationship among the operation detector, the midair image and thedetection reference, in (b) and (c)

FIG. 4 A schematic illustration of a midair image displayed for purposesof calibration processing in the first embodiment

FIG. 5 The calibration processing executed in the first embodiment,illustrated in (a), (b), (c) and (d) each providing a sectional viewindicating the relationship among the operation detector, the midairimage, the detection reference and the finger position

FIG. 6 A flowchart of the calibration processing executed in a firstcalibration processing mode in the first embodiment

FIG. 7 An illustration indicating the positional relationship among themidair image, the detection reference and the reach position in a secondcalibration processing mode in the first embodiment

FIG. 8 A flowchart of the calibration processing executed in the secondcalibration processing mode in the first embodiment

FIG. 9 A block diagram showing the main configuration of the displaydevice achieved in variation 1 of the first embodiment

FIG. 10 The calibration processing executed in variation 1 of the firstembodiment, illustrated in (a), (b) and (c) each providing a sectionalview indicating the relationship among the operation detector, themidair image, the detection reference and the finger position

FIG. 11 A flowchart of the calibration processing executed in variation1 of the first embodiment

FIG. 12 A schematic illustration of a midair image displayed forpurposes of calibration processing in variation 3 of the firstembodiment

FIG. 13 The calibration processing executed in variation 3 of the firstembodiment, illustrated in (a), (b) and (c) each providing a sectionalview indicating the relationship among the operation detector, themidair image, the detection reference and the finger position

FIG. 14 A flowchart of the calibration processing executed in variation3 of the first embodiment

FIG. 15 A schematic illustration of a midair image displayed forpurposes of calibration processing in variation 4 of the firstembodiment

FIG. 16 A flowchart of the calibration processing executed in variation4 of the first embodiment

FIG. 17 A block diagram showing the main configuration of the displaydevice achieved in variation 6 of the first embodiment

FIG. 18 A schematic illustration of a midair image displayed forpurposes of calibration processing in variation 6 of the firstembodiment

FIG. 19 A flowchart of the calibration processing executed in variation6 of the first embodiment

FIG. 20 A schematic presentation of a midair image displayed invariation 7 of the first embodiment in a plan view in (a) and in asectional view indicating the relationship among the operation detector,the midair image and the detection reference in (b)

FIG. 21 The calibration processing executed in variation 7 of the firstembodiment, illustrated in (a), (b) and (c) each providing a sectionalview indicating the relationship among the operation detector, themidair image, the detection reference and the finger position

FIG. 22 A perspective of the display device achieved in variation 8 ofthe first embodiment

FIG. 23 A block diagram showing the main configuration of the displaydevice achieved in variation 8 of the first embodiment

FIG. 24 A sectional view of the internal structure assumed in thedisplay device in variation 8 of the first embodiment

FIG. 25 A block diagram showing the main configuration of the displaydevice achieved in a second embodiment

FIG. 26 A flowchart of the calibration processing executed in the secondembodiment

FIG. 27 A block diagram showing the main configuration of the displaydevice achieved in a third embodiment

FIG. 28 A flowchart of the calibration processing executed in the thirdembodiment

FIG. 29 Illustrations of the display device achieved in a fourthembodiment, with the structure of the display device schematicallyillustrated in a sectional view in (a) and an electronic apparatus atwhich the display device is fitted shown in a perspective in (b)

FIG. 30 A block diagram showing the main configuration of the displaydevice achieved in the fourth embodiment

FIG. 31 A plan view of the operation detector included in the displaydevice achieved in the fourth embodiment

FIG. 32 An illustration of the structure and the functions of theoperation detector achieved in the fourth embodiment

FIG. 33 A schematic illustration showing the structure adopted in thedisplay device achieved in variation 1 of the fourth embodiment

FIG. 34 A schematic illustration showing another structure that may beadopted in the display device in variation 1 of the fourth embodiment

FIG. 35 The structure of the display device achieved in a fifthembodiment, illustrated in a disassembled oblique view in (a) and in asectional view in (b)

FIG. 36 A block diagram showing the main configuration of the displaydevice achieved in the fifth embodiment

FIG. 37 The calibration processing executed in the fifth embodiment,illustrated in (a) and (b) each providing a sectional view indicatingthe relationship among the midair image, the detection reference and thefinger position.

FIG. 38 A flowchart of the calibration processing executed in the fifthembodiment

FIG. 39 A flowchart of the calibration processing executed in thedisplay device achieved in variation 3 of the fifth embodiment

FIG. 40 A block diagram showing the main configuration of the displaydevice achieved in variation 4 of the fifth embodiment

FIG. 41 An illustration of a midair image displayed for purposes ofcalibration of the display device achieved in variation 4 of the fifthembodiment

FIG. 42 A schematic presentation of a midair image displayed in a sixthembodiment in a sectional view indicating the relationship among theoperation detector, the midair image and the detection reference

FIG. 43 The calibration processing executed in the display device in thesixth embodiment, illustrated in (a) and (b) each providing a sectionalview indicating the relationship among the midair image, the detectionreference and the finger position

FIG. 44 The calibration processing executed in the display device in thesixth embodiment, illustrated in (a) and (b) each providing a sectionalview indicating the relationship among the midair image, the detectionreference and the finger position

FIG. 45 The calibration processing executed in variation 1 of the sixthembodiment, illustrated in (a), (b) and (c) each providing a sectionalview indicating the relationship among the midair image, the detectionreference and the finger position.

FIG. 46 A block diagram showing the main configuration of the displaydevice achieved in a seventh embodiment

FIG. 47 A schematic presentation of a midair image displayed in aneighth embodiment in a plan view in (a), in a sectional view indicatingthe relationship among the operation detector, the midair image and thedetection reference in (b) and a perspective of the detection referencein (c)

FIG. 48 A schematic presentation of examples of specific non-contactoperations that may be performed in the eighth embodiment

FIG. 49 A schematic illustration showing a specific non-contactoperation detected in the detection reference in the eighth embodiment

FIG. 50 Schematic illustrations, each showing the specific non-contactoperation not detected in the detection reference in the eighthembodiment, with (a) showing the specific non-contact operation in itsentirety detected outside the detection reference above the detectionreference and (b) showing the specific non-contact operation detectedoutside the detection reference below the detection reference

FIG. 51 Illustrations showing how the detection reference position maybe changed in the eighth embodiment, with (a) showing the detectionreference position before the change and (b) showing the detectionreference position changed upward

FIG. 52 Illustrations showing how the detection reference position maybe changed in the eighth embodiment, with (a) showing the detectionreference position before the change and (b) showing the detectionreference position changed downward

FIG. 53 Illustrations showing how the detection reference position maybe changed in the eighth embodiment, with (a) showing the detectionreference position before the change and (b) showing the detectionreference position changed to the right

FIG. 54 Schematic illustrations, each showing the specific non-contactoperation not detected at the detection reference in the eighthembodiment, with (a) showing part of the specific non-contact operationdetected outside the detection reference above the detection referenceand the remaining non-contact operation detected at the detectionreference and (b) showing part of the specific non-contact operationdetected outside the detection reference below or to a side of thedetection reference and the remaining non-contact operation detected atthe detection reference

FIG. 55 A flowchart of the calibration processing executed in the eighthembodiment

FIG. 56 Illustrations of part of the specific non-contact operationdetected at the detection reference in variation 2 of the eighthembodiment, with the detection reference changed in (a) and thedetection reference not changed in (b)

FIG. 57 A block diagram showing the main configuration of the displaydevice 1 achieved in variation 3 of the eighth embodiment

FIG. 58 The calibration processing executed in variation 3 of the eighthembodiment, illustrated in (a) and (b) each providing a sectional viewindicating the relationship among the operation detector, the detectionreference and the finger position

FIG. 59 A flowchart of the calibration processing executed in variation3 of the eighth embodiment

FIG. 60 The calibration processing executed in variation 6 of the eighthembodiment, illustrated in (a) and (b) each providing a sectional viewindicating the relationship among the operation detector, the detectionreference and the finger position

FIG. 61 The calibration processing executed in variation 6 of the eighthembodiment, illustrated in (a) and (b) each providing a sectional viewindicating the relationship among the operation detector, the detectionreference and the finger position

DESCRIPTION OF EMBODIMENTS First Embodiment

In reference to drawings, the display device achieved in the firstembodiment will be described. The first embodiment will be described inreference to an example in which the display device in the embodiment ismounted in a portable telephone. It is to be noted that the displaydevice in the embodiment may be mounted in an electronic apparatus otherthan a portable telephone such as a portable information terminal devicesuch as a tablet terminal, a wristwatch-type terminal and so on, apersonal computer, a music player, a land-line telephone unit or awearable device.

FIG. 1(a) is a disassembled oblique view of a display device 1 and FIG.1(b) shows part of the display device 1 in an enlarged side elevation.It is to be noted that for purposes of facilitating the explanation, acoordinate system assuming an X axis, a Y axis and a Z axis is setrelative to the display device 1 as indicated in the figure. It is to bealso noted that the coordinate system set for these purposes does notneed to be an orthogonal coordinate system assuming the X axis, the Yaxis and the Z axis, and it may instead be a polar coordinate system ora cylindrical coordinate system. In other words, any of these coordinatesystems may be set relative to the display device, as long as the X axisis set to extend along the shorter sides of the rectangular display areaof the display device 1, the Y axis is set to extend along the longersides of the rectangular display area of the display device 1 and the Zaxis is set to extend along a direction perpendicular to the displayarea.

The display device 1 includes a body 10 having installed therein acontrol unit 20, a display unit 11, an image forming optical system 12and an operation detector 13. The display unit 11, the image formingoptical system 12 and the operation detector 13 are disposed inside thebody 10. The display unit 11, configured with, for instance, a liquidcrystal display or an organic EL display, includes a plurality ofdisplay pixel arrays arranged in a two-dimensional pattern. Undercontrol executed by the control unit 20, the display unit 11 displays animage corresponding to display image data. The image forming opticalsystem 12 is disposed further upward relative to the display unit 11 (onthe + side along the Z direction) over a predetermined distance from thedisplay unit 11. The image forming optical system 12 may be configuredby, for instance, layering two micro-lens arrays, each having convexmicro-lenses 121 arranged in a two-dimensional array, along the Zdirection as clearly indicated in FIG. 1(b).

The image forming optical system 12 forms a midair image 30 of a displayimage displayed at the display unit 11 in the space above the displaydevice 1. Namely, an image displayed by the display unit 11 at thedisplay device 1 can be viewed by the user of the display device 1 asthe midair image 30, floating above the display device 1. The midairimage 30 includes a plurality of icons 30A (operation buttons)corresponding to operation buttons via which various settings may beselected for the display device 1 and instructions for executing variousfunctions of the display device 1 may be issued. The icons 30A in theembodiment may be set over, for instance, three rows by five columns. Itis to be noted that instead of the micro-lens arrays, pinhole arrays orslit arrays may be used to configure the image forming optical system.

The operation detector 13, disposed further upward (on the + side alongthe Z direction) relative to the image forming optical system 12, may beconfigured with, for instance, a transparent capacitive panel (hereafterwill be referred to as a capacitive panel) of the known art. Theoperation detector 13 configured with a capacitive panel forms anelectric field with electrodes constituted of a substantiallytransparent material. When the user moves his finger or a stylus towardthe midair image 30 in order to operate manipulate adjust the displayposition of the midair image 30, the operation detector 13 detects theposition of the finger or the stylus as an electrostatic capacitancevalue. For instance, it may compare the electrostatic capacitance valuesdetected at the four corners of the capacitive panel so as to detect theposition of the user's finger along the X axis and the Y axis based onthe electrostatic capacitance values detected at the four corners. Theoperation detector 13 may take an electrostatic capacitance detectionrange, which is a predetermined range set upward relative to itself, aswill be described in detail later, and detect the distance (i.e., theposition on the Z axis) between the operation detector 13 and the fingeror the stylus within the predetermined detection range based on theelectrostatic capacitance values detected at the four corners of thetransparent capacitive panel by, for instance, comparing theelectrostatic capacitance values detected at the four corners. Themidair image 30 must be formed via the image forming optical system 12so that it occupies a position within the predetermined detection rangeof the operation detector 13, and preferably a position around themidway point of the predetermined detection range along the up/downdirection. As described above, the operation detector 13 detects anoperation by a user at the display position of the midair image 30 withhis finger or with a stylus, enabling the user to perform operations onthe midair image 30 without having to directly touch the operationdetector 13. It is to be noted that while the following description willbe provided by assuming that the user uses his finger to perform anoperation at the display position of the midair image 30, the similarmanner will apply to an operation performed via a stylus or the like.

FIG. 2 is a block diagram showing the control unit 20, and the displayunit 11 and the operation detector 13 controlled by the control unit 20,among the components configuring the display device 1. The control unit20, comprising a CPU, a ROM, a RAM and the like, includes an arithmeticoperation circuit that controls various structural elements of thedisplay device 1, including the display unit 11 and the operationdetector 13, based on a control program and executes various types ofdata processing. The control unit 20 includes an image generation unit201, a display control unit 202, a calibration unit 203, a detectionreference control unit 204 and a storage unit 205. The storage unit 205includes a nonvolatile memory where the control program is stored, astorage medium where image data to be displayed at the display unit 11and the like are stored, and the like. It is to be noted that thecorrespondence between the distance from the surface of the operationdetector 13 to the fingertip and the electrostatic capacitancemanifesting when the operation detector 13 detects the fingertip isstored in advance in the storage unit 205. Accordingly, as the fingertipis positioned within the predetermined detection range of the operationdetector 13, the operation detector 13 is able to detect theelectrostatic capacitance at the fingertip, and thus detect the positionof the fingertip along the Z direction based on the detectedelectrostatic capacitance and the correspondence stored in the storageunit 205, as explained earlier.

Based upon image data stored in the storage medium, the image generationunit 201 generates display image data corresponding to a display imageto be displayed at the display unit 11. The display control unit 202brings up the image corresponding to the display image data generated bythe image generation unit 201 at the display unit 11. As the userperforms an operation at the display position of an icon 30A in themidair image 30, the display control unit 202 executes display imageswitchover control for the display unit 11 in correspondence to the typeof icon 30A that has been operated. It is to be noted that in responseto a user operation performed at the display position of the icon 30A inthe midair image 30, the display control unit 202 may execute controlother than the display image switchover control for the display unit 11.For instance, assuming that the user performs an operation at thedisplay position of the icon 30A in the midair image 30 while a movieimage is on display as the display image at the display unit 11, thedisplay control unit 202 may execute control for playing the movie imagecurrently displayed at the display unit 11 or for stopping the movieimage playback.

The calibration unit 203 executes calibration processing in first andsecond calibration processing modes, as will be described in detaillater. The detection reference control unit 204 sets a detection plane,i.e., a detection reference, in the space above the display device 1,and specifically, at the position of the midair image 30 (or over aspecific range around the midair image 30) within the predetermineddetection range of the operation detector 13. The detection referencecontrol unit 204 also decides that the user's finger has reached thedetection reference based on an electrostatic capacitance value detectedby the operation detector 13. Namely, the detection reference controlunit 204 decides that the user has performed an operation at the displayposition of the icon 30A when the finger position (the position on the Xaxis, the Y axis and the Z axis) corresponding to the value of theelectrostatic capacitance detected by the operation detection unit 13matches the position of the detection reference having been set. Thedetection reference control unit 204 may set the detection reference ata predetermined specific initial position and changes or adjusts thedetection reference position based on the results of the calibrationprocessing to be described later. The initial position for the detectionreference is stored in advance in the storage unit 205. It is to benoted that the initial position for the detection reference may be auniversal position shared by all users, or a different initial positionmay be set for each user based on the history of use of the displaydevice 1 by the particular user. The initial position for the detectionreference and a newly changed position for the detection reference maybe set over the entire plane (the X axis and the Y axis) of theoperation detector 13 or may be set over part of the plane. Thedetection reference having been set when the display device 1 was lastused, stored in the storage unit 205, may also be read out and set asthe initial position for the detection reference. It is to be noted thatthe detection reference control unit 204 may decide that the user hasperformed an operation at the display position of the icon 30A when thefinger position corresponding to the electrostatic capacitance valuedetected by the operation detector 13 roughly matches the position forthe detection reference, as well as when the finger position exactlymatches the position for the detection reference. A specific range overwhich the finger position is considered to roughly match the positionfor the detection reference may be set in advance.

FIG. 3(a) presents an example of a midair image 30 that may be displayedby the display device 1 and FIG. 3(b) schematically illustrates thepositional relationship among the body 10 or the operation detector 13,the midair image 30 and a detection reference 40. The midair image 30 inFIG. 3(a) includes 15 icons 30A set over three rows by five columns, asexplained earlier. In FIG. 3(b), the detection reference 40 is set nearthe position of the midair image 30, and specifically, slightly abovethe midair image 30, as shown in the figure, by the detection referencecontrol unit 204. In FIG. 3(b), icons in the midair image 30 areindicated as 30A marked with bold dotted lines. It is to be noted thatwhile the icons 30A all assume a height wise position matching that ofthe midair image 30 since they are part of the midair image 30, the bolddotted lines indicating the icons 30A are offset from the position ofthe solid line indicating the midair image 30 in FIG. 3(b) so as todistinguish them from the midair image 30.

In FIG. 3(b), the midair image 30 is formed above the operation detector13 in the display device 1, at a position set apart from the operationdetector 13 by a distance H1, whereas the detection reference 40 is setat a position further upward relative to the operation detector 13, setapart from the operation detector 13 by a distance H2 (H1<H2). Asexplained earlier, the operation detector 13 assumes an electrostaticcapacitance detection range 13A set above its surface. In FIG. 3(b), theelectrostatic capacitance detection limit above the operation detector13 is indicated with a dotted line 13 a, and the interval between theelectrostatic capacitance detection limit 13 a and the operationdetector 13 is indicated as an electrostatic capacitance detection range13A. The midair image 30 and the detection reference 40 are set so as totake positions within the electrostatic capacitance detection range 13A.It is to be noted that while the detection reference 40 in FIG. 3(b) isset above the midair image 30, it may instead be set further downwardrelative to the midair image 30 or may be set so as to match theposition of the midair image 30, as long as it takes a position withinthe electrostatic capacitance detection range 13A of the operationdetector 13. A range outside the area set for the detection reference 40within the detection range 30A will hereafter be referred to as outsidea detection reference 41.

It is to be noted that while the midair image 30 and the detectionreference 40 are shown in FIG. 3(b) as flat planes ranging parallel tothe XY plane, they do not need to be flat planes but instead may becurved planes. The detection reference 40 may include stages, eachcorresponding to one of the icons 30A, as indicated in FIG. 3(c),instead of being formed as a flat plane. In other words, the distancebetween a given icon 30A and the part of the detection reference 40corresponding to the particular icon may be different from the distancebetween another icon 30A and the part of the detection reference 40corresponding to the other icon. Assuming stages in the detectionreference 40, as described above, is particularly effective when themidair image 30 is a 3-D image and the positions of the plurality oficons 30A are offset relative to one another along the Z direction,i.e., along the up/down direction. By offsetting the positions of thedetection reference 40, each corresponding to one of the icons 30A incorrespondence to the offset with which the plurality of icons 30A inthe 3-D midair image 30 are shifted along the up/down direction, forinstance, it is also possible that the distances between the icons 30Aand the corresponding positions in the detection reference 40 remainequal.

When the user's fingertip has moved to a point set apart from theoperation detector 13 by the distance H2, the operation detector 13outputs a detection output corresponding to the distance H2. Based uponthe detection output provided by the operation detector 13, thedetection reference control unit 204 decides that the user's fingertipposition has matched the detection reference 40 and accordingly decidesthat the user has performed an operation with his fingertip at thedisplay position of the icon 30A. Through this process, the displaydevice 1 detects an operation by the user at the display position of theparticular icon 30A in the midair image 30 and executes a functioncorresponding to the icon 30A having been operated. For instance, itexecutes display image switchover at the display unit 11.

While the icons 30A take positions set apart from the operation detector13 by the distance H1, they are displayed as part of the midair image 30and for this reason, the visual perception of the display positions ofthe icons 30A in the midair image 30, i.e., their height H1, of one usermay be different from that of another user. The visual perception of thedisplay positions of the icons 30A of a given user may change dependingupon the environment in which he operates the display device 1. Forinstance, when the detection reference 40 is set so as to align with theposition of the midair image 30, a user, having moved his finger towardan icon 30A in the midair image 30 in order to perform an operation atthe display position of the particular icon 30A, may feel that there isstill some distance between his finger and the icon 30A although thefinger has, in fact, reached the icon, i.e., the detection reference 40.Under such circumstances, an icon operation will be executed against theuser's wishes. Another user, having moved his finger toward an icon 30Ain the midair image in order to perform an icon operation, may feel thathis finger has reached the icon 30A and is performing an operation atthe display position of the icon 30A while his finger is actually stillset apart from the icon 30A, i.e., the detection reference 40. In thiscase, no icon operation will be executed against the user's wishes. Ineither scenario, the user is bound to feel that the icon operation isuncomfortable.

Accordingly, in addition to a midair operation mode that may be set forthe midair image 30, as described earlier, a calibration processing modecan be set in the display device 1 in the embodiment, so as to customizethe response to icon operations to suit the user. In the calibrationprocessing mode, the positional relationship between the midair image 30and the detection reference 40 is set so as to establish a suitablerelation best suited to the operational perception or operationcharacteristics of a specific user, the environment in which the displaydevice is used and the like. As explained earlier, first and secondcalibration processing modes are available in the display device 1 inthe embodiment. In the first calibration processing mode, calibrationprocessing is executed while the midair image operation mode is not ineffect, i.e., while midair image operation mode execution is notunderway, whereas in the second calibration processing mode, calibrationprocessing is executed while the midair image operation mode execution,following startup of the display device 1, is underway. The processingin the first and second calibration processing modes is executed by thecalibration unit 203 shown in FIG. 2. It is to be noted that the firstor second calibration processing mode may be selected by operating acalibration processing mode selector operation button (not shown)located at the display device 1, and the control unit 20 may select andexecute the midair image operation mode when neither the firstcalibration processing mode nor the second calibration processing modeis selected via the calibration processing mode selector operationbutton. If the display device does not have a calibration processingmode selector operation button, the second calibration processing modemay be a default mode. The first calibration processing mode and thesecond calibration processing mode will now be described in that order.It is to be noted that the first or second calibration processing modemay be selected via an icon in the midair image instead of via anoperation button.

The first calibration processing mode will be described first. As thedisplay device 1 is started up and the user operates the calibrationprocessing mode selector operation button to select the firstcalibration processing mode, the calibration unit 203 in FIG. 2 startsthe first calibration processing mode. The image generation unit 201generates display image data, and the display unit 11 brings up adisplay image to be used in calibration processing based on the displayimage data. FIG. 4 and FIG. 5 show a midair image 300 of the displayimage generated for the calibration processing. The midair image 300includes an icon 300A for calibration, and a message “executecalibration. Please touch this icon” is superimposed on the calibrationicon 300A. The detection reference control unit 204 may select aninitial setting for the detection reference 40 so as to set it at aposition near the midair image 30, e.g., slightly above the midair image300, as indicated in FIG. 5(a). The initial position for the detectionreference 40 may instead be set so as to align with the midair image 300or may be set slightly below the midair image 300. It is to be notedthat it is not always necessary to display the message “executecalibration. Please touch this icon” when calibration processing is tobe executed. For instance, the user, having selected the calibrationprocessing mode may already know a specific operation he needs toperform in the calibration processing mode and in such a case, themessage does not need to be displayed.

As the user, following the instructions in the message superimposed onthe icon 300A in the midair image 300, moves his fingertip F down towardthe icon 300A, as shown in FIG. 5(a), until the fingertip F reaches theelectrostatic capacitance detection range 13A of the operation detector13 shown in FIG. 2, the operation detector 13 detects movement of theuser's fingertip F toward the icon 300A, i.e., the downward movement, asa change in the electrostatic capacitance.

As the fingertip F moves further down and reaches a position indicatedby a dotted line 50 slightly above the detection reference 40 in FIG.5(b), the user feels that his fingertip F, having reached the displayposition of the icon 300A, has performed a press down operation on theicon 300A, and moves the fingertip F upward by a predetermined distance.The operation detector 13 detects the downward movement of the fingertipF described above, i.e., the fingertip F pressing down the icon 300A,and the subsequent upward movement by the predetermined distance aschanges in the electrostatic capacitance. Once the operation detector 13detects the fingertip F pressing down the icon 300A and the subsequentupward movement of the fingertip F by the predetermined distancedescribed above, the detection reference control unit 204 decides thatan operation has been performed at the display position of the icon300A. It is to be noted that the reach position to which the user'sfingertip F moves downward in order to press down the icon 300A for anoperation at the display position of the icon 300A before the fingertipF moves upward by the predetermined distance will be referred to as areach position. Namely, position indicated by the dotted line 50 will bereferred to as the reach position.

Upon deciding that the fingertip F, having reached the reach position50, has performed an operation at the display position of the icon 300A,the detection reference control unit 204 moves, i.e., changes, thedetection reference 40 to the reach position 50 as indicated in FIG.5(c) and also stores the position data indicating the position of thechanged detection reference 40 into the storage unit 205 in FIG. 2. Itis to be noted that the detection reference control unit 204 may insteadmove, i.e., change, the detection reference 40 to a position furtherupward relative to the reach position 50, set apart from the reachposition 50 by a predetermined distance d1, as indicated in FIG. 5(d)and store position data indicating the position of the changed detectionreference 40 into the storage unit 205. This predetermined distance d1may be set to, for instance, approximately 1 mm through 10 mm. Thepredetermined distance d1 may be changed in correspondence to each userwho operates the device, and in such a case, the predetermined distanced1 may be set based on the distance measured from the tip of the user'sfinger to the first joint. For instance, the predetermined distance d1may be set to a specific value falling into a range between ¼ and ½ ofthe distance from the user's fingertip to the first joint.

While the reach position 50 to which the finger reaches is furtherupward relative to the detection reference 40 in the example describedabove, the reach position 50 may instead be further downward relative tothe detection reference 40, and in such a case, too, decision-makingwith regard to the reach position 50 should be made as described aboveand the detection reference 40 should be changed based on the reachposition 50 thus determined. While decision-making with regard to thereach position 50 aligned with the detection reference 40 is alsoexecuted as described above, the detection reference 40 may not bechanged in this case, since the reach position 50 is aligned with thedetection reference 40.

It is to be noted that when the reach position 50 is further downwardrelative to the detection reference 40, the finger passes through thedetection reference 40 and the detection reference control unit 204 thusdecides that the finger has reached the detection reference 40 based onthe detection output provided by the operation detector 13 before thefinger reaches the reach position 50. In this situation, no displayswitchover takes place at the display unit 13 in the first calibrationprocessing mode. Likewise, when the reach position 50 is aligned withthe detection reference 40, no display switchover takes place at thedisplay unit 13. However, when the finger has moved to reach thedetection reference 40, the user may be informed that the finger hasreached the detection reference with, for instance, a highlight displayof the icon 300A or by flashing the icon 300A.

It is to be noted that while the user presses down the icon 300A as anoperation performed at the display position of the icon 300A in theexample described above, the present invention is not limited to thisexample. Namely, the operation detector 13 may detect a predeterminednon-contact operation performed by the user in relation to the icon 300Aand, in such a case, the detection reference 40 may be changed based onthe location where the specific non-contact operation is performed. Thepredetermined non-contact operation may be performed by the user bymaking a gesture operation to touch the icon 300A. In this case, thedetection reference 40 may be changed based on the position at which theuser has made the gesture of touching the icon 300A. The operationperformed by the user making a gesture of touching the icon 300A may be,for instance, a gesture of swiping the icon 300A with the user's hand.The position at which the user has performed the operation by making agesture of touching the icon 300A may be determined based on theposition at which the user's hand, having made the swiping gesture, isdetermined to have stopped or based on the position at which the userhas started making the swiping gesture.

As described above, it is decided in the first calibration processingmode that the user perceives that his finger has performed an operationat the display position of the icon 300A in the midair image 300 bydetecting a shift from a downward movement to an upward movement by thepredetermined distance, and the positional relationship between thedetection reference 40 and the midair image 30 is changed by changingthe detection reference 40 for the particular user to a position setapart from the finger reach position 50 by the predetermined distance d1along the upward direction. Namely, based on the operation by the user,which is one type of information on the user operating the device, thepositional relationship between the detection reference 40 and thedisplay position of the midair image 300 is changed. It is to be notedthat when changing the detection reference 40 for a given user, it isnot always necessary to detect the identity of the user operating thedevice and that the positional relationship between the detectionreference 40 but the display position of the midair image 300 may bechanged based on the detection output provided by the operation detector13 having detected the operation described above.

It is to be noted that the detection reference control unit 204,changing the position of the detection reference 40, may move the entiredetection reference 40 or may move only the part of the detectionreference 40 corresponding to the icon 300A operated by the user'sfinger.

It is to be also noted that in the description provided above, thedetection reference 40 is changed to the position further upward setapart from the reach position 50 by the predetermined distance d1 in theexample presented in FIG. 5(c) for the following reason. Namely, a useroperating a touch panel normally touches the touch panel with his fingerand gently presses the finger down on the touch panel. When the userperforms an operation at the display position of the icon 300A in themidair image 300, he tends to simulate this process, i.e., whenperforming the operation at the display position of the icon 300A in themidair image 300 with his fingertip, the user is likely to move hisfinger slightly downward before moving it upward by a predetermineddistance, instead of immediately moving his finger upward by thepredetermined distance after the operation at the display position.Accordingly, the finger reach position 50 tends to be slightly lowerthan the position at which the user perceives that the operation hasbeen performed at the display position of the icon 300A with the fingerand the detection reference 40 is then changed to the position set apartfrom the reach position 50 by the predetermined distance d1 along theupward direction. However, the extent to which the finger is moved downto press the icon 300A may be relatively small or the finger may hardlymove downward to touch the icon 300A, for some users, and accordingly,the position of the detection reference 40 may be changed so as tosubstantially match the reach position 50.

In the calibration processing mode, which is selected in order to setthe positional relationship between the calibration midair image 300 andthe detection reference 40 to a suitable relationship suited to theoperation characteristics of the user, as explained earlier, thedetection reference 40 may be changed so as to be substantially alignedwith the reach position 50, as described above, or to a position furtherdownward relative to the reach position 50, in correspondence to theoperation characteristics by the user or the display device. Forinstance, when the reach position 50 of a given user is above the midairimage 300 and the distance between the reach position 50 and the upperlimit 13 a of the electrostatic capacitance detection range 13A is lessthan the distance between the reach position 50 and the midair image300, the detection reference 40 may be changed so as to be in alignmentwith the reach position 50 or to a position further downward relative tothe reach position 50, since the detection reference 40 changed to takea position further upward relative to the reach position 50 would be tooclose to the upper limit 13 a of the electrostatic capacitance detectionrange 13A.

It is to be noted that the method through which the reach position 50 isdetermined is not limited to that described above, through which thereach position 50 is determined based on the shift from the downwardmovement to the upward movement by the predetermined distance, and itmay be determined through any of the various other methods to bedescribed below. For instance, the user, perceiving that his finger,having reached the display position of the icon 300A, has performed thepress down operation on the icon 300A, stops moving his finger downward,i.e., stops pressing down the icon. The detection reference control unit204 may decide that the finger has stopped pressing down when there isnot almost any change in the value of the electrostatic capacitancedetected by the operation detector 13, and may determine the position atwhich the finger has stopped pressing down as the reach position 50. Itis to be noted that it may decide that the downward movement has stoppedwhen the value of the electrostatic capacitance detected by theoperation detector 13 has remained unchanged for a short span of timeof, for instance, 0.1 sec through 1 sec. In another method, the reachposition may be determined by detecting the velocity vector of themovement of the user's finger, i.e., the finger movement velocity andthe finger movement direction, based on a change in the electrostaticcapacitance, by detecting that the direction of the finger velocityvector has changed from the downward direction to the opposite directionand that the velocity vector along the opposite direction has reached apredetermined level, and by designating the position taken by the fingerwhen the velocity vector achieving the predetermined level along theopposite direction is detected as the reach position. When thepredetermined level for the velocity vector is set substantially equalto 0 in this method, the position taken by the finger when the directionof the velocity vector shifts from downward to the opposite direction,i.e., the lowermost position, will be determined to be the reachposition, whereas when the predetermined level is set to a value otherthan 0 in this method, a position taken by the finger, set apart fromthe lowermost position by a predetermined distance along the upwarddirection is determined as the reach position. As explained above, thereach position is set at the lowermost position taken by the finger asthe finger is judged by the detection reference control unit 405 to haveperformed an operation at the display position of the icon or at aposition near the lowermost position.

While the reach position is determined in the example presented above inreference to the part of the finger or the stylus coming in contact withthe icon 300A in the midair image 300, i.e., the position of thefingertip or the position of the lowermost part of the stylus, the reachposition may instead be determined in reference to the position of thefingernail tip of the user's finger or in reference to the position ofthe first joint of the finger. The icon may be also operated with theuser's foot or elbow instead of the user's finger, and in such a case,the reach position may be determined in reference to the foot or theelbow. When the icon operation is performed via a stylus, a specificposition on the stylus may be marked and the reach position may bedetermined in reference to the marked position. It is desirable thatwhen the reach position is determined in reference to the position ofthe first joint of the finger, the position of the stylus mark or thelike, the operation detector 13 be configured with an image-capturingdevice or the like, such as that to be described in reference tovariation 8, instead of the capacitive panel.

The relationship between the first calibration processing mode describedabove and the midair image operation mode will be described in referenceto the flowchart presented in FIG. 6. After the display device 1 isstarted up, the processing shown in the flowchart presented in FIG. 6 isexecuted based on a program by the control unit 20. The program isstored in the storage unit 205. In step S1, the first calibrationprocessing mode, selected by the user via the calibration mode selectoroperation button, is recognized, and then the operation proceeds to stepS2. In step S2, the calibration unit 203 shown in FIG. 2 starts thefirst calibration processing mode before the operation proceeds to stepS3. In step S3, the image generation unit 201 generates display imagedata for the calibration display image, the display control unit 202brings up on display at the display unit 11 the calibration image basedon the display image data and the detection reference control unit 204sets the detection reference at the initial position. The display imageat the display unit 11 is the calibration midair image 300 in FIG. 4generated by the image forming optical system 12. The midair image 300includes the icon 300A with the message “execute calibration. Pleasetouch this icon”. In step S4, the operation detector 13 detects adownward movement of the user's fingertip F, and the operation proceedsto step S5.

In step S5, the detection reference control unit 204 shown in FIG. 2determines based on the detection output provided by the operationdetector 13, whether or not the finger has reached the reach position.When an affirmative decision is made in step S5, i.e., when it isdecided that the finger has reached the reach position, the operationproceeds to step S6. When a negative decision is made in step S5, i.e.,when it is decided that the finger has not become still, the operationwaits in standby until an affirmative decision is made. In step S6, thedetection reference control unit 204 changes the position of thedetection reference 40 based on the reach position 50 and stores theposition data indicating the position of the changed detection reference40 into the storage unit 205 shown in FIG. 2 before the operationproceeds to step S7. In step S7, the operation exits the firstcalibration processing mode and proceeds to step S8. In step S8, themidair image operation mode is started, and the operation then proceedsto step S9. In step S9, the midair image 30 for the midair imageoperation mode shown in FIG. 3, which includes icons 30A, is displayed,the position data indicating the position of the detection reference 40having been changed in the first calibration processing mode throughstep S6 are read out from the storage unit 205 and the detectionreference 40 is set at a position near the midair image 30 based on theposition data, as indicated in FIG. 3(b). The detection reference 40,having been set in the first calibration processing mode to suit theoperation characteristics of the user is thus used in the midair imageoperation mode.

As the user moves his finger down toward the midair image 30 in order toperform an operation at the display position of an icon 30A, theoperation detector 13 shown in FIG. 2 detects the downward movement ofthe user's finger in step S10, and then the operation proceeds to stepS11. In step S11, the detection reference control unit 204 determinesbased on the detection output divided by the operation detector 13whether or not the finger has reached the detection reference 40. Whenan affirmative decision is made in step S11, i.e., when it is decidedthat the finger has reached the detection reference 40, the operationproceeds to step S12. When a negative decision is made in step S11,i.e., when it is decided that the finger has not reached the detectionreference 40, the operation waits in standby until an affirmativedecision is made. In step S12, the display control unit 202 switches thedisplay image at the display unit 13 to a display image corresponding tothe icon 30A having been operated, and then the operation proceeds tostep S13. In step S13, a decision is made as to whether or not anoperation has been performed to stop the display device 1. When anaffirmative decision is made in step S13, i.e., when an operation hasbeen performed to stop the display device 1, the display device 1 stops.When a negative decision is made in step S13, however, the operationreturns to step S10.

As explained above, the detection reference is changed based on anoperation by the user so as to change the positional relationshipbetween the midair image and the detection reference in the firstcalibration mode. Since the detection reference for the midair imageoperation mode is set at the position of the detection reference havingbeen changed through the first calibration mode, the midair imageoperation mode can be executed based on the detection reference suitablefor the operation characteristics of the user or the operatingenvironment in which the display device 1 is operated.

While the first calibration processing mode is executed immediatelyafter the display device 1 is started up so as to precede the midairimage operation mode in the example described above, the firstcalibration processing mode may instead be executed following the midairimage operation mode. For instance, the user, having experiencedfrustration while performing an operation at the display position of anicon 300A in the midair image operation mode, may operate thecalibration processing mode selector operation button at the displaydevice 1 in order to select the first calibration processing mode. Inthis case, the first calibration processing mode is executed byinterrupting the midair image operation mode that is underway and themidair image operation mode is then resumed after the first calibrationprocessing ends. It is to be noted that while the display device 1selects the first calibration mode in response to an operation of theoperation button by the user in the example described above, the firstcalibration processing mode may instead be executed upon detecting signsof annoyance experienced by the user, which is likely attributable todifficulty in performing an operation at the display position of theicon 300A. The display device 1 may, for instance, read the pulse rateof the user (biometrics) and a pulse rate exceeding a predeterminedvalue may be detected as a sign of user discomfort.

Next, the second calibration processing mode will be described inreference to FIG. 7 and FIG. 8. It is to be noted that the processingdescribed earlier in reference to the first calibration mode may also beexecuted, as appropriate, in the second calibration processing modedescribed below. FIG. 7 illustrates the midair image 30 on display forthe midair image operation mode, the detection reference 40 at theinitial position and the finger reach position 50, whereas FIG. 8presents a flowchart of the operation executed in the second calibrationprocessing mode. The processing in the flowchart presented in FIG. 8 isexecuted following startup of the display device, by the control unit 20based on a program.

In step S41, the second calibration processing mode is recognized as theselected mode, and then the operation proceeds to step S42. In step S42,the midair image operation mode and the second calibration processingmode start concurrently, before the operation proceeds to step S43. Instep S43, the midair image 30 shown in FIG. 3, which includes the icons30A, is displayed and the detection reference control unit 204 in FIG. 2sets the detection reference 40 at a predetermined initial position,e.g., at the position taken by the midair image 30 or at a positionslightly above the position taken by the midair image 30, before theoperation proceeds to step S44. At this time, a message “calibrationexecuted during icon operation” is briefly displayed in the midair image30. However, it is not necessary that this message be displayed.

As the user moves his finger downward in order to perform an operationat the display position of an icon 30A, the operation detector 13 startsdetection of finger movement in step S44, and then the operationproceeds to step S45. In step S45, the detection reference control unit204 determines based on the detection output provided by the operationdetector 13 whether or not the finger moving downward has passed throughthe detection reference 40. When an affirmative decision is made in stepS45, i.e., when the finger moving downward has passed through thedetection reference 40 and has moved further down, the operationproceeds to step S46. F1 in FIG. 7 indicates the finger having passedthrough the detection reference 40 during its downward movement. In stepS46, the detection reference control unit 204, having decided that thefinger F1 has reached the detection reference 40, i.e., it has passedthrough the detection reference 40, executes icon display switchover soas to switch the midair image 30 in correspondence to the icon 30Ahaving been operated. The operation then proceeds to step S47. In stepS47, the detection reference control unit 204 determines whether or notthe finger F1 has reached the reach position 50, and when an affirmativedecision is made, the operation proceeds to step S48, whereas when anegative decision is made, the operation is held until an affirmativedecision is made. In step S48, the detection reference control unit 204changes the position of the detection reference 40 based on the reachposition 50. It is to be noted that the position of the detectionreference 40 having been changed may be exactly at the user's fingertipor may be above the position of the user's fingertip. In such a case,icon display switchover does not occur since icon display switchover hasalready been executed once in step S46.

When a negative decision is made in step S45, i.e., when the fingermoving downward has not yet passed through the detection reference 40,the operation proceeds to step S49. In step S49, the detection referencecontrol unit 204 determines based on the detection output provided bythe operation detector 13 whether or not the finger has reached thereach position 50, and when an affirmative decision is made, theoperation proceeds to step S50. When, on the other hand, a negativedecision is made, the operation is held until an affirmative decision ismade. A finger F2 in FIG. 7 indicates that the reach position 50 is inalignment with the detection reference 40. In step S50, the detectionreference control unit 204 determines based on the detection output fromthe operation detector 13 whether or not the reach position 50 is inalignment with the detection reference 40, and when an affirmativedecision is made, the operation proceeds to step S51, whereas when anegative decision is made, the operation proceeds to step S52. In stepS51, icon display switchover is executed since the reach position 50 isin alignment with the detection reference 40 but the detection reference40 is not changed.

In step S52, with the reach position 50 located above the detectionreference 40 as indicated by a finger F3 in FIG. 7, the detectionreference control unit 204 changes the position of the detectionreference 40 based on the reach position 50, i.e., changes the positionof the detection reference 40 to a point near the reach position 50, andthen the operation proceeds to step S55. In this situation, when theposition of the detection reference 40 having been changed is exactly atthe user's fingertip or is further upward relative to the position ofthe user's fingertip, icon display switchover is executed. When, on theother hand, the detection reference 40 having been changed still doesnot reach the position of the user's fingertip, icon display switchoveris not executed.

In step S55, a decision is made as to whether or not an end operationhas been performed in order to exit the second calibration processingmode, and when an affirmative decision is made, the operation proceedsto step S55, whereas when a negative decision is made, the operationreturns to step S44.

In the second calibration processing mode described above, which isexecuted concurrently while the midair image operation mode is underway,the user is able to perform an operation at the display position of themidair image by using the detection reference suitable for the userwithout having to be aware that calibration processing is also inprogress. It is to be noted that the first/second calibration processingmode selection does not necessarily need to be made by the user andinstead, the display device 1 may automatically select either the firstcalibration processing mode or the second calibration processing mode.It is not necessary that both the first calibration processing mode andthe second calibration processing mode be available at the displaydevice 1 and the display device 1 may use one of these calibrationmodes.

The display device 1 achieved in the first embodiment as described aboveallows for the following variations.

Variation 1 of the First Embodiment

The display device in variation 1 calculates the velocity or theacceleration of the user's fingertip based on the detection outputprovided by the operation detector 13, predicts a finger reach positionbased on the velocity or the acceleration having been calculated andchanges the detection reference based on the predicted reach position.FIG. 9 is a block diagram showing a control unit 20 and a display unit11 and an operation detector 13 controlled by the control unit 20, amongthe structural components in the display device 1 achieved in variation1.

The structural features of the display device 1 in variation 1 will bedescribed by focusing on features different from those in the displaydevice achieved in the first embodiment. A velocity/accelerationdetection unit 206 in FIG. 9 reads out an electrostatic capacitancevalue detected by the operation detector 13 over predetermined timeintervals, calculates the velocity of the finger movement based on achange occurring in the electrostatic capacitance value over eachpredetermined time interval and also calculates the acceleration of thefinger movement based on the velocity having been calculated. A reachposition predicting unit 207 predicts the reach position for the fingerbased on the finger movement velocity or acceleration output by thevelocity/acceleration detection unit 206. The reach position predictingunit 207 is able to estimate the reach position for the finger by, forinstance, detecting that the moving finger, having been accelerating ormoving at a substantially constant speed, has shifted into adecelerating state and ascertaining the rate of deceleration. Based uponthe reach position predicted by the reach position predicting unit 207,the detection reference control unit 204 changes the detectionreference.

Next, the first calibration processing mode executed in the displaydevice 1 in variation 1 will be explained in reference to FIG. 10 andFIG. 11. The processing executed in steps other than step S103 throughstep S107 in the flowchart presented in FIG. 11 is identical to that inthe flowchart presented in FIG. 6, and accordingly, a repeatedexplanation is not provided. As the fingertip F moves into thepredetermined detection range 13A of the operation detector 13, as shownin FIG. 10(a), the operation detector 13 detects the movement of thefingertip F as a change in the electrostatic capacitance value in stepS104. In step S105, the velocity/acceleration detection unit 206calculates the velocity and the acceleration of the movement of thefingertip F based on the detection output provided by the operationdetector 13. In step S106, the reach position predicting unit 207calculates the reach position for the fingertip F based on the velocityand the acceleration of the movement having been calculated by thevelocity/acceleration detection unit 206. The finger reach positioncalculated by the reach position predicting unit 207, i.e., predicted bythe reach position predicting unit 207, is indicated by a dotted line 60in FIG. 10(b). In step S107, the detection reference control unit 204changes the detection reference 40 based on the predicted reach position60, as indicated in FIG. 10(c) and also stores the position dataindicating the changed position of the detection reference 40 into thestorage unit 205. In the subsequent step S110, the detection referencefor the midair image operation mode is set at the position of thedetection reference 40 indicated in the position data having beenstored. It is to be noted that the reach position for the finger may beestimated based on both the velocity and the acceleration of the fingermovement or based on either one of them.

It is to be noted that while the velocity/acceleration detection unit206 reads out the electrostatic capacitance value detected by theoperation detector 13 over predetermined time intervals, calculates thevelocity of the finger movement based on a change occurring in theelectrostatic capacitance value over each predetermined time intervaland calculates the acceleration of the finger movement based on thevelocity thus calculated in the description provided above, the presentinvention is not limited to this method and it may be adopted inconjunction with a velocity/acceleration detection unit 206 configuredwith an image-capturing device. While the velocity or the accelerationof the user's finger movement is calculated in the example describedabove, the velocity or the acceleration of the movement of the user'sfoot or elbow or the movement of a stylus pen held by the user may becalculated instead.

It is to be also noted that while the predicted reach position 60, towhich the user's finger is predicted to reach, is calculated based onthe velocity and the acceleration of the user's finger having beencalculated and the detection reference 40 is changed based on thepredicted reach position 60 thus calculated for the user's finger in thedescription provided above, it is not necessary to predict the reachposition 60 for the user's finger for each operation. When a predictedreach position 60 is calculated based on an unintended movement of theuser's finger occurring prior to an operation by the user, the detectionreference may not be set at the suitable position, and instead, thedetection reference 40 may be set to, for instance, an extremely highposition. Such an undesirable result may be prevented by changing theposition of the detection reference 40 based on a predicted reachposition 60 that is calculated only when a velocity and an accelerationof the user's finger movement, indicated by a value equal to or greaterthan a predetermined threshold value, are detected.

In variation 1, in which the finger reach position is predicted based onthe velocity or the acceleration of finger movement, calibrationprocessing can be executed promptly.

While the calibration processing in this variation is adopted in thefirst calibration processing mode in the first embodiment in the exampledescribed above, the calibration processing may also be adopted in thesecond calibration processing mode. By adopting variation 1 in thesecond calibration processing mode, it becomes possible to estimate inadvance the reach position for the fingertip F of the user performing amidair image operation before the fingertip F reaches the detectionreference 40 and to change the detection reference based on thepredicted reach position. This means that even when the fingertip F ofthe user does not reach the detection reference 40, the user iscomfortably able to perform an operation since an error such as afailure to execute icon display switchover can be prevented.

Variation 2 of the First Embodiment

In the first embodiment and variation 1 of the first embodiment, thedisplay device 1 detects or predicts the reach position, changes thedetection reference based on the reach position and stores the positiondata for the detection reference into the storage unit 205 through asingle calibration processing session. Subsequently, the detectionreference for the midair image operation mode is set to or changed tothe position of the detection reference stored in the storage unit 205.The display device achieved in variation 2 is distinct in that itindividually stores a plurality of detection reference positions eachset through one of a plurality of calibration processing sessions intothe storage unit 205 and changes the detection reference for the midairimage operation mode based on the plurality of positions of thedetection reference stored in the storage unit.

In the first calibration processing session, the detection referencecontrol unit 204 determines the finger reach position 50 based on thedetection output provided by the operation detector 13, changes thedetection reference 40 based on the reach position 50 and stores theposition data for the detection reference 40 into the storage device205. Immediately after the first session, it executes a secondcalibration processing session and stores position data for thedetection reference changed in a similar manner into the storage unit205. It may further execute a third calibration processing sessionimmediately afterwards. A single detection reference position is thencalculated by using the plurality of sets of position data for thedetection reference having been stored into the storage unit 205 throughthe plurality of calibration processing sessions having been executedsuccessively as described above, and position data for the detectionreference thus calculated are stored into the storage unit 205. In thesubsequent midair image operation mode, the detection reference is setto the position of the calculated detection reference indicated in theposition data stored in the storage unit 205.

A single detection reference may be determined by using the plurality ofdetection references 40 through any of various procedures. For instance,the single detection reference may be calculated as the arithmetic meanof the plurality of detection references 40 or as the geometric mean ofthe plurality of detection references 40. As an alternative, a newdetection reference may be determined by applying suitable weight toeach of the plurality of detection references 40. For instance, adetection reference may be calculated by weighting the position H_(N) ofa detection reference determined through an Nth session and the positionH_(N+1) of a detection reference determined through an N+1th session ata ratio of 3:7. In more specific terms, by using H_(N) and H_(N+1), adetection reference can be calculated as expressed as;(H_(N)×3+H_(N+1)×7)/10. The weighting ratio used in this calculation isnot limited to 3:7 and the number of sessions is not limited to 2,either. It will be also obvious that instead of individually storingdetection positions, each set based on the finger reach positiondetermined through one of a plurality of calibration processingsessions, into the storage unit 205, the finger reach positions, eachdetected through one of a plurality of calibration processing sessionsmay be each stored into the storage unit 205 and a single detectionreference may be calculated based on the plurality of reach positionsthus stored.

The position of the detection reference may not be changed through thecalibration processing when the distance between the reach position andthe detection reference is equal to or less than a predetermined value,i.e., when the reach position is close to the detection reference.

Instead of changing the detection reference through each calibrationprocessing session, the number of times an operation at the icon displayposition has failed may be calculated based on the number of times thatthe reach position has been determined and the number of times the reachposition has been judged to actually reach the detection referencethrough a plurality of calibration processing sessions and the detectionreference may be changed when the number of times a failure has occurredis judged to be equal to or greater than a predetermined value.

While the calibration processing in this variation is adopted in thefirst calibration processing mode in the first embodiment in the exampledescribed above, the calibration processing may also be adopted in thesecond calibration processing mode and in variation 1.

The calibration processing described above, in which the reach positionis determined by detecting a natural operating motion that the userwould normally make when performing an operation at an icon displayposition in a midair image, e.g., a downward movement of the finger topress down the icon, which then shifts to an upward movement or amovement of the finger coming into contact with the icon, and thenholding down the icon briefly, can be executed without the user beingaware of the reach position being detected • determined through thecalibration processing, i.e., without the user being aware thatcalibration processing is in progress.

Variation 3 of the First Embodiment

In the first embodiment, the reach position is determined by detectingan operation performed at the display position of the midair image bythe user with his finger and the detection reference is changed based onthe reach position thus determined. As an alternative, the user may beallowed to designate the finger position at which he has a perception ofperforming an operation at the display position of an icon in the midairimage, and in such a case, the detection reference control unit maydetermine the designated position and change the positional relationshipbetween the detection reference and the midair image by changing thedetection reference based on the designated position. The following is adescription of a variation in which the user indicates the position atwhich he has had a perception of performing an operation at the displayposition of the midair image as a designated position. It is to be notedthat while an example in which variation 3 is adopted in the firstcalibration processing mode in the first embodiment is described below,it may also be adopted in the second calibration processing mode and invariations 1 and 2 described earlier.

The following is a description of the display device achieved invariation 3. As the display device 1 is started up and the user operatesthe calibration processing mode selector operation button to select thefirst calibration processing mode, the calibration unit 203 in FIG. 2starts the first calibration processing mode. The image generation unit201 generates display image data, and the display unit 11 brings up adisplay image to be used in the calibration processing based on thedisplay image data. FIG. 12 shows a midair image 300 as the displayimage generated for the calibration processing. The midair image 300includes an icon 300B for calibration, and a message “executecalibration. Please point at icon with finger and move the fingersideways” is superimposed on the calibration icon 300B. The detectionreference control unit 204 may set the detection reference 40 to aninitial position near the midair image 300, as indicated in FIG. 13(a).

As the user, following the instructions in the message superimposed onthe icon 300B in the midair image 300, moves his fingertip F down towardthe icon 300B, as shown in FIG. 13(a), until the fingertip F reaches theelectrostatic capacitance detection range 13A of the operation detector13 shown in FIG. 2, the operation detector 13 detects movement of theuser's fingertip F toward the icon 300B, i.e., the downward movement, asa change in the electrostatic capacitance. It is to be noted that FIG.13(a) presents a front view of the finger.

The user moves his finger further downward and upon feeling that thefingertip F has reached the display position of the icon 300B in themidair image 300, he moves the finger F sideways, as indicated by thearrow in FIG. 13(b). The operation detector 13 detects the downwardmovement and the lateral movement of the finger F. The detectionreference control unit 204 decides that the operation detector 13, hasdetected the downward movement of the finger, then having detected thelateral movement of the finger, determines the position assumed by thefinger along the height-wise direction when the shift from the downwardmovement to the lateral movement has occurred as a designated position50A. Based upon the designated position 50A, the detection referencecontrol unit 204 changes the position of the detection reference 40 andstores the position data for the changed detection reference 40 into thestorage unit 205. It is to be noted that while the designated position50A is located further upward relative to the midair image 300 in FIG.13(b), the designated position 50A, i.e., the position at which the userhas a perception that his fingertip F has reached the icon 300B in themidair image 300, may be in alignment with the midair image 300 or maybe further down relative to the midair image 300.

It is to be noted that the detection reference control unit 204designates the height-wise position taken by the finger when the shiftfrom the downward movement to the lateral movement has occurred as thedesignated position 50A in the description provided above, the presentinvention is not limited to this example and it may instead designatethe height of the finger at the end of the lateral movement followingthe downward movement as the designated position 50A. As a furtheralternative, the detection reference control unit 204 may designate theaverage or the median of the heights of the finger assumed during theperiod of time elapsing between the start of the lateral movement of thefinger and the end of the lateral finger movement as the designatedposition 50A.

In reference to the flowchart presented in FIG. 14, the calibrationprocessing executed in variation 3 will be described. It is to be notedthat the flowchart in FIG. 14 shows the processing executed in stepsS121 through S129 and does not show the processing executed insubsequent steps. The processing executed in step S129 and subsequentsteps is similar to the processing executed in step S109 and subsequentsteps in the flowchart presented in FIG. 11.

The processing executed in step S121 through step S124 is similar tothat executed in step S1 through step S4 in the flowchart presented inFIG. 6. In step S126, the operation detector 13 detects the lateralmovement of the user's finger. In step S127, the detection referencecontrol unit 204 decides, based on the detection output from theoperation detector 13, that a shift has occurred in the finger movementfrom the downward movement to the lateral movement, designates theposition taken by the finger at the time of the shift as the designatedposition 50A, changes the position of the detection reference 40 basedon the designated position 50A and stores the position data for thechanged detection reference 40 into the storage unit 205, before theoperation proceeds to step S128. In step S128, the first calibrationprocessing mode ends and the operation proceeds to step S129. In stepS129, the midair image operation mode starts. In the midair imageoperation mode, the detection reference is set based on the positiondata for the changed detection reference 40 read out from the storageunit 205.

While the calibration processing in variation 3 is in progress, the userdesignates a position at which he has the perception of having performedan operation at the display position of the midair image with his fingerby switching the finger movement from the downward movement to a lateralmovement. In other words, the calibration processing is executed byallowing the user to designate a position perceived operation positionwith respect to the icon 300B as the display position and thus, accuratecalibration processing is enabled. Indicating the designated position byswitching the finger movement from the downward movement to a lateralmovement assures good operability and the calibration processing can beexecuted promptly.

Variation 4 of the First Embodiment

The user operating the display device 1 in variation 3 indicates theposition at which he has a perception of performing an operation at theicon display position with his finger as a designated position byswitching his finger movement from the downward movement to a lateralmovement. The user of the display device 1 achieved in variation 4indicates the position at which he has a perception of performing anoperation at the icon display position with his finger by operatinganother icon. The calibration processing executed in this variation willbe described next. It is to be noted that while an example in whichvariation 4 is adopted in the first calibration processing mode in thefirst embodiment is described below, it may also be adopted in thesecond calibration processing mode and in variations 1 through 3described earlier.

As the display device 1 is started up and the user operates thecalibration processing mode selector operation button to select thefirst calibration processing mode, the calibration unit 203 in FIG. 2starts the first calibration processing mode. The image generation unit201 generates display image data, and the display unit 11 brings up adisplay image to be used in calibration processing based on the displayimage data. FIG. 15 shows a midair image 300 of the display imagegenerated for the calibration processing. The midair image 300 includesicons 300C and 300D for calibration, and a message “execute calibration.Please touch the icon on the left side with a finger of your left handwhile pointing to this icon with a finger of your right hand” issuperimposed on the calibration icon 300C. It is to be noted that theicon 300C and the icon 300D are set side-by-side, the icon 300C on theright hand-side and the icon 300D on the left hand-side.

As the user, following the instructions in the message superimposed atthe icon 300C, moves a fingertip of his right hand down toward the icon300C in order to perform an operation at the display position of theicon 300C and the fingertip reaches the electrostatic capacitancedetection range 13A of the operation detector 13, the operation detector13 detects the movement of the user's finger moving closer to thedisplay position of the icon 300C, i.e., the downward movement of thefinger, as a change in the electrostatic capacitance. The user moves hisfinger further downward and as soon as he has the perception of thefingertip performing an operation at the display position of the icon300C in the midair image 300, he moves a fingertip of his left handtoward the icon 300D in order to perform an operation at the displayposition of the icon 300D with the fingertip of his left hand asdirected in the message. The operation detector 13 detects the movementof the fingertip toward the icon 300D. The detection reference controlunit 204 recognizes the position taken by the fingertip in the user'sright hand at the time point at which the operation detector 13 detectsthat the user's finger is positioned on the icon 300D as the designatedposition 50A. The detection reference control unit 204 changes thedetection reference 40 based on the designated position 50A and storesthe position data for the changed detection reference 40 into thestorage unit 205.

It is to be noted that since the position taken by the right hand-sidefinger when the user has the perception of performing an operation atthe display position of the right hand-side icon 300C is designated asthe designated position, the right hand-side finger needs to move downtoward the midair image. However, the left hand-side finger needs to bepositioned above or below the icon 300D to perform an operation at thedisplay position of the left hand-side icon 300D and thus, it is notalways necessary to move the left hand-side finger downward. Namely, theleft hand-side finger may move along, for instance, a direction parallelto the plane of the midair image 300, i.e., along a lateral direction,until it reaches a point above or below the icon 300D.

It is not necessary that a left hand-side finger and a right hand-sidefinger be used, as long as the operations described above can be alsodetected both on the icon 300C and on the icon 300D in the calibrationmidair image 300. For instance, these operations may be performed byusing two fingers of one hand on either side. Instead of performing anoperation at the display position of the icon 300D, the user may pressan OK button (not shown) at the display device 1 in variation 4.

Instead of recognizing the position taken by the right hand-sidefingertip when the user performs an operation at the display position ofthe icon 300D or when the user presses the OK button (not shown) as thedesignated position, the position of the right hand-side fingertipassumed when the user makes a predetermined gesture with his left handmay be also recognized as the designated position. In such a case, thedisplay device 1 should include an image-capturing device 18 invariation 8 to be described later (see FIG. 22) so that a user gesture(e.g., the hand switching from the sign “stone” to the sign “paper”) isdetected by using images obtained via the image-capturing device 18.

In reference to the flowchart presented in FIG. 16, the calibrationprocessing executed in the variation will be described. It is to benoted that the flowchart in FIG. 16 shows the processing executed insteps S131 through S139 and does not show the processing executed insubsequent steps. The processing executed in step S139 and subsequentsteps is similar to the processing executed in step S109 and subsequentsteps in the flowchart presented in FIG. 11.

The processing executed in step S131 through step S133 is similar tothat executed in step S1 through step S3 in the flowchart presented inFIG. 6. In step S134, the operation detector 13 starts detection of adownward movement of the fingertip in the user's right hand. The usermoves his finger further downward and then performs an operation at thedisplay position of the icon 300D with his left hand-side fingertip atthe time point at which he has the perception of the right hand-sidefingertip performing an operation at the display position of the icon300C in the midair image 300. In step S136, the position taken by theright hand-side fingertip at the time point at which the user hasperformed an operation at the display position of the icon 300D with hisleft hand in step S135, is designated as the designated position 50A,and then the operation proceeds to step S137. In step S137, thedetection reference control unit 204 changes the detection reference 40based on the designated position 50A and stores the position data forthe changed detection reference 40 into the storage unit 205 before theoperation proceeds to step S138. In step S138, the first calibrationprocessing mode ends and the operation proceeds to step S139. In stepS139, the midair image operation mode starts.

The user of the display device 1 achieved in variation 4 described aboveindicates the designated position at which the finger operates the iconduring the calibration processing by operating another icon or byoperating the OK button at the display device 1. The calibrationoperation allowing the user to designate the position at which heperceives an icon 300, can be executed with high accuracy. By allowingthe user to indicate the designated position through an operation atanother icon or at a button at the display device, the calibrationprocessing can be executed promptly.

Variation 5 of the First Embodiment

The user of the display device achieved in variation 5, perceiving thathe has performed an operation at the display position of an icon withhis fingertip, indicates the designated position by holding the fingerstill for a predetermined length of time. It is to be noted that whilean example in which variation 5 is adopted in the first calibrationprocessing mode in the first embodiment is described below, it may alsobe adopted in the second calibration processing mode and in variations 1through 4 described earlier.

In this variation, a message “execute calibration. Please point at thisicon and hold the finger still for a moment” is displayed withsuperimposed on an icon included in the calibration midair image. Theuser, perceiving that he has performed an operation at the icon displayposition, holds the finger still for a moment and in response, theoperation detector 13 detects cessation of the downward movement of thefinger over a predetermined length of time. The detection referencecontrol unit 204 recognizes the position at which the finger is heldstill as the designated position based on the detection output providedby the operation detector 13 at this time.

The designated position is determined as described below. Namely, it isdecided that an operation has been performed at the display position ofthe icon 300A when the fingertip F, having been moving downward, comesto a stop and holds still within a relatively small predeterminedholding range taken along the up/down direction over a length of timeequal to or greater than a predetermined time interval. It is decidedthat an operation has been performed at the display position of the icon300A with the fingertip F when the fingertip F stays within the specificholding range over the predetermined time interval or longer, asdescribed above, since the operation at the display position of the icon300A in the midair image 300 is different from an operation performed ata touch panel and the fingertip F may not become completely still at thedisplay position of the icon 300A. It is to be noted that thepredetermined holding range in reference to which the designatedposition is determined should be set to a value sufficiently smallrelative to the electrostatic capacitance detection range 13A of theoperation detector 13, e.g., 5 mm, and the predetermined time intervalshould be set to, for instance, 2 sec.

Variation 6 of the First Embodiment

The user of the display device achieved in variation 6 indicates thedesignated position at which he has a perception of performing anoperation at an icon display position with his voice. It is to be notedthat while an example in which variation 6 is adopted in the firstcalibration processing mode in the first embodiment is described below,it may also be adopted in the second calibration processing mode and invariations 1 through 5 described earlier.

FIG. 17 is a block diagram showing a control unit 20, and a display unit11 and an operation detector 13 controlled by the control unit 20, amongthe structural components in the display device 1 achieved in variation6. The display device 1 includes a sound collector 14, with a sounddetection unit 208 installed in the control unit 20. The sound collector14 collects sound around the display device 1 and outputs the collectedsound as audio data to the sound detection unit 208. The sound collector14 may be a commonly available microphone. The sound detection unit 208recognizes the audio data provided from the sound collector 14 anddetermines whether or not the audio data express the word “yes”.

After the calibration unit 203 in FIG. 17 starts up the firstcalibration processing mode, the image generation unit 201 generatesdisplay image data, and the display unit 11 brings up a display image tobe used in the calibration processing based on the display image data.FIG. 18 shows a midair image 300 as the display image generated for thecalibration processing. The midair image 300 includes an icon 300E forcalibration, and a message “execute calibration. Please touch icon andsay “yes”” is superimposed on the calibration icon 300E.

The user, following the instructions in the message displayed withsuperimposed on the icon 300E, movies his fingertip down toward the icon300E in order to perform an operation at the display position of theicon 300E and says “yes” as directed in the message when he perceivesthat his fingertip has touched the icon 300E. The operation detector 13detects the downward movement of the fingertip, and the sound collector14 picks up the user's voice and outputs it as audio data to the sounddetection unit 208. As the sound detection unit 208 decides that theaudio data correspond to “yes”, the detection reference control unit 204recognizes the position taken by the fingertip, detected by theoperation detector 13 at the exact time point, as the designatedposition 50A, changes the detection reference 40 based on the designatedposition 50A and stores the position data for changed detectionreference 40 into the storage unit 205.

In reference to the flowchart presented in FIG. 19, the calibrationprocessing executed in the variation will be described. It is to benoted that the flowchart in FIG. 19 shows the processing executed insteps S141 through S149 and does not show the processing executed insubsequent steps. The processing executed in step S149 and subsequentsteps is similar to the processing executed in step S109 and subsequentsteps in the flowchart presented in FIG. 11.

The processing executed in step S141 through step S144 is similar tothat executed in step S1 through step S4 in the flowchart presented inFIG. 6. In step S145, the sound detection unit 208 determines whether ornot the user has said “yes” based on the output from the sound collector14. When an affirmative decision is made in step S145, i.e., when it isdecided that the user, perceiving that he has touched the icon 30F, hassaid “yes”, the operation proceeds to step S146. When, on the otherhand, a negative decision is made in step S145, the operation waits instandby until an affirmative decision is made. In step S146, thedetection reference control unit 204 determines, i.e., designates, theposition taken by the fingertip at the time point at which the sounddetection unit 208 has recognized the word “yes” as the designatedposition 50A. In step S147, the detection reference control unit 204changes the detection reference 40 based on the designated position 50Aand stores the position data for the changed detection reference 40 intothe storage unit 205 before the operation proceeds to step S148. In stepS148, the first calibration processing mode ends and the operationproceeds to step S149. In step S149, the midair image operation modestarts.

The user of the display device 1 achieved in variation 6 described abovevocally indicates the designated position taken by his finger when heperceives that an operation has been performed at the icon displayposition. By allowing the reach position to be designated with thevoice, the calibration processing can be executed promptly.

It is to be noted that the display device 1 does not need to include thesound collector 14 and the sound detection unit 208 in such aconfiguration may execute sound detection by using audio data input froman external sound collecting device via either a wireless means or awired means.

Variation 7 of the First Embodiment

The detection reference is a single plane or planes defined in stages inthe description provided above. However, the detection reference may beformed as an area with a depth instead of as a plane. Calibrationprocessing that may be executed for a detection reference forming suchan area will be explained next. It is to be noted that while an examplein which variation 7 is adopted in the first calibration processing modein the first embodiment is described below, it may also be adopted inthe second calibration processing mode and in variations 1 through 6described earlier.

The display device 1 in this variation is similar to the display device1 described in reference to the first embodiment, assuming a structureshown in the block diagram in FIG. 2. FIG. 20(a) presents an example ofa midair image 30 that may be displayed in the midair image operationmode by the display device 1 in the variation, whereas FIG. 20(b)provides a schematic presentation of the positional relationship amongthe body 10 or the operation detector 13, the midair image 30 and thedetection reference 40. The midair image 30 in FIG. 20(a) is similar tothe midair image 30 shown in FIG. 3(a). The detection reference 40 inFIG. 20(b) is set as an area located between an upper plane 401 and alower plane 402, achieving a depth d2 along the up/down direction.

In FIG. 20(b), the midair image 30 is formed at a position furtherupward relative to the operation detector 13 of the display device 1 andset apart from the operation detector 13 by a distance H1, with theupper plane 401 and the lower plane 402 of the detection reference 40set above the operation detector 13, apart from the operation detector13 by a distance H3 and a distance H4 respectively (H1<H3<H4). Namely,d2=H4−H3. The midair image 30 and the detection reference 40 are setwithin the electrostatic capacitance detection range 13A. It is to benoted that while the detection reference 40 is set further upwardrelative to the midair image 30 in the example presented in FIG. 3(b),it may instead be set downward relative to the midair image 30 or may beset so that the position of the midair image 30 is within the area d2 aslong as the detection reference 40 remains within the electrostaticcapacitance detection range 13A of the operation detector 13.

As the user's fingertip enters the detection reference 40, the operationdetector 13 outputs a detection output corresponding to a point withinthe range between the distance H3 and the distance H4 that matches theposition of the fingertip, and when the detection output provided by theoperation detector 13 corresponds to a point in the range between thedistance H3 and the distance H4, the detection reference control unit204 decides that an operation has been performed at the display positionof an icon 30A with the fingertip. The display device 1 thus detects theoperation by the user at the display position of an icon 30A in themidair image 30 and executes the function corresponding to theparticular icon 30A having been operated. The display device 1 may, forinstance, execute display image switchover at the display unit 11. Thedetection reference control unit 204 in the display device in variation7 described above decides that an operation has been performed at thedisplay position of an icon 30A with the user's finger in the midairimage operation mode regardless of exactly which position is assumed bythe finger within the depth-wise range d2 of the detection reference 40,making it possible to detect an operation performed at the displayposition with better reliability. For instance, the finger may notalways start its descent from a point directly above the icon 30A andinstead may start moving downward diagonally from a point not directlyabove the icon 30A. In the case of a flat plane detection reference 40such as that shown in FIG. 3, the finger moving diagonally downward maypass through a point beside the icon 30A instead of passing through thepart of the detection reference 40 directly above the icon 30A, and itmay not be possible to determine with regard to an operation performedat the display position of the icon 30A with the finger. However, entryof the finger into the detection reference 40 having the depth d2 can bedetected with a reliability even when the finger moves down from a pointdiagonally above the detection reference 40 and thus, the occurrence ofdetection failure can be reduced. Even when the finger moves parallel tothe midair image 30 to perform an operation at the display position ofthe icon 30A, entry of the finger into the detection reference 40 withthe depth d2 can be detected with reliability at the display device invariation 7.

The processing executed in the first calibration processing mode at thedisplay device 1 in variation 7 with the detection reference 40 assumingthe depth d2 as described above will be explained next. It is to benoted that the processing in the second calibration processing mode maybe executed through a similar procedure in relation to the detectionreference 40 having the depth d2. In addition, features identical tothose in the first embodiment will not be explained below.

In the first calibration processing mode, a midair image 300 thatincludes the icon 300A shown in FIG. 4 is displayed and the detectionreference 40 is set at the initial position, as shown in FIG. 21(a). Theuser, following the instructions in the message displayed withsuperimposed on the icon 300A, moves his fingertip F down toward theicon 300A in order to perform an operation at the display position ofthe icon 300A and as the fingertip F reaches the electrostaticcapacitance detection range 13A of the operation detector 13 shown inFIG. 2, the operation detector 13 detects the movement of the user'sfinger F toward the icon 300A, i.e., the downward movement of the user'sfinger F, as a change in the electrostatic capacitance.

The user, perceiving that an operation has been performed at the displayposition of the icon 300 with his finger, as shown in FIG. 21(b), moveshis fingertip F upward by a specific distance. The operation detector 13detects the downward movement of the fingertip F, i.e., the fingertip Fpressing down the icon 300 and the subsequent upward movement by aspecific distance as a change in the electrostatic capacitance. Basedupon the change in the electrostatic capacitance, the detectionreference control unit 204 determines the reach position 50 or thedesignated position 50A, as described earlier.

Based upon the reach position 50 or the designated position 50A, thedetection reference control unit 204 alters the detection reference 40to a detection reference 40 occupying a three-dimensional area with thedepth d2, as shown in FIG. 21(c). While the detection reference 40having the depth d2 is set so as to contain the reach position 50 or thedesignated position 50A in the example presented in FIG. 21(c), thedetection reference 40 with the depth d2 may instead be set at aposition above or below the reach position 50 or the designated position50A. A three-dimensional area, present between the position set apartfrom the reach position 50 or the designated position 50A by apredetermined distance along the direction opposite from the directionin which the user moves his finger to press down the icon and the reachposition 50 or the designated position 50A, may be designated as thedetection reference 40 with the depth d2. The detection referencecontrol unit 204 stores the position data for the detection reference 40with the depth d2 into the storage unit 205. As the midair imageoperation mode is subsequently executed, the detection reference 40 withthe depth d2 is set based on the position data stored in the storageunit 205.

The processing in the midair operation mode is executed in relation tothe first calibration processing mode described above through aprocedure similar to that in the flowchart presented in FIG. 6 exceptfor the following point. Namely, the detection reference control unit204 sets the detection reference 40 as a single plane based on the reachposition 50 in step S6 in the first embodiment. Variation 7 differs fromthis in that the detection reference 40 with the depth d2 is set basedon the reach position 50 or the designated position 50A.

It is to be noted that calibration processing may be executed in themidair image operation mode each time an icon is operated so as to setthe detection reference 40 by positioning a plane, which includes thereach position 50 taken by the user fingertip or the designated position50A, at a midway point between the upper plane 401 and the lower plane402 of the detection reference 40.

As long as the fingertip is positioned above the icon used forcalibration processing, the reach position or the designated positioncan be determined even when the user's finger moves downward diagonally,i.e., with an angle relative to the Z direction.

Variation 8 of the First Embodiment

While the downward movement of the user's fingertip is detected by theoperation detector 13 configured with a capacitive panel in thedescription provided above, the position of the user's fingertip may bedetected by an image-capturing device instead. The display device 1 invariation 8 includes an image-capturing device (e.g., a digital camera)18 to function as an operation detector, disposed at the upper surfaceof the display device 1, as shown in FIG. 22. A block diagram pertainingto such a display device 1 is provided in FIG. 23.

The control unit 20 of the display device 1 in the block diagrampresented in FIG. 23 includes an image analysis unit 209. Theimage-capturing device 18 captures an image of an object located abovethe display unit 11, e.g., the user's finger, and the captured image isinput to the image analysis unit 209. The image analysis unit 209determines the position of the user's fingertip by analyzing thecaptured image input from the image-capturing device 18. Namely, theimage analysis unit 209 decides, based on the position of the image ofthe finger within the captured image, a specific icon, among theplurality of icons, being operated with the user's fingertip. The imageanalysis unit 209 may compare the size of the finger image within thecaptured image with a standard finger size, and specifically, with thesize of a finger at a predetermined height-wise position, an image ofwhich has been captured in advance, so as to determine the height wiseposition of the finger, i.e., the position taken by the descendingfinger. Through this process, the position of the user's fingertipwithin the three-dimensional space can be determined. The display device1 in variation 8 structured as described above is capable of obtaining,through analysis of the captured image provided via the image-capturingdevice 18, information similar to the information relating to thefingertip position obtained via the operation detector 13 configuredwith the capacitive panel. Thus, the display device in variation 8 isable to execute processing similar to that executed in the embodimentand the variations described earlier, by using the image-capturingdevice 18 instead of the capacitive panel having been described inreference to the embodiment and the numerous variations thereof.

While the image analysis unit 209 in the display device 1 in variation 8calculates the height wise position of the finger based on the size ofthe finger in the captured image, the image-capturing device 18 mayinstead detect the height wise position of the finger via a phasedifferent focus detection device and an image recognition device mountedin the digital camera. In more specific terms, the image recognitiondevice may recognize a finger, the phase different focus detectiondevice may detect a defocus quantity with respect to the fingerrecognized by the image recognition device and the height wise positionof the finger may be calculated based on the defocus quantity. Theheight wise position of the finger may be likewise detected via acontrast focus detection device mounted in the digital camera instead ofthe phase different focus detection device.

It may be ideal to configure the image-capturing device 18 with a camerahaving installed therein a TOF (time of flight) device instead of aphase different focus detection device or a contrast focus detectiondevice. A TOF camera emits infrared radiation from the camera body,receives infrared light that is reflected off a target object and thenenters the TOF camera and calculates the distance from the TOF camera tothe target object based on a phase change having occurred in thereceived light relative to the emitted light. Accordingly, bydesignating the user's fingertip as the measurement target object,emitting infrared light from the TOF camera toward the user's fingertipand receiving light reflected from the fingertip, the distance from theTOF camera to the user's fingertip can be determined. It is desirablethat the image-capturing device 18 include an image-capturing lensconstituted with a wide-angle lens so as to cover the entire midairimage 30 and such an image-capturing lens may be a fisheye lens. Thedisplay device may include a plurality of image-capturing devices (e.g.,two image-capturing devices) and the position of the user's fingertipmay be detected based on captured images provided from the plurality ofimage-capturing devices.

FIG. 24 presents an example of a display device 1 equipped with a TOFcamera. FIG. 24 simply shows the internal structure of the displaydevice 1 and does not provide an illustration of the display devicebody. As FIG. 24 shows, an installation space for a TOF camera 118′ isformed so as to take up a position corresponding to the centers of thedisplay unit 11 and an image forming optical element 12 and the TOFcamera 118′ is disposed in this installation space. The TOF camera 118′radiates infrared light onto the user's fingertip by scanning infraredlight over a predetermined range and measures the distance from the TOFcamera 118′ to the user's fingertip based on a change in the phase ofreflected light. Based upon the distance and the infrared emissiondirection, the position of the user's fingertip in three-dimensionalspace relative to the TOF camera 118′ can be determined. In other words,the specific position within the midair image plane corresponding to thefingertip position and the distance that sets the fingertip positionapart from the surface of the display device 1 can be determined.Information similar to detection information indicating the fingertipposition obtained in conjunction with a capacitive panel can thus beobtained based on the range-finding results provided by the TOF camera118′. It is to be noted that while an installation space for the TOFcamera 118′ is formed so as to take up an area corresponding to thecenters of the display unit 11 and the image forming optical system 12and the TOF camera 118′ is disposed in this space in the descriptionprovided above, the present invention is not limited to this example andit may be adopted in a configuration that includes a TOF camera 118′installed outside the display unit 11.

At the display device 1 in variation 8, too, the midair image 30 isformed at a position above the image forming optical system 12 of thedisplay device 1, set apart from the image forming optical system 12 bya distance H1, and the detection reference 40 is set at a position abovethe image forming optical system 12, apart from the image formingoptical system 12 by a distance H2 (H1<H2), as shown in FIG. 24. Theimage-capturing device 18 assumes a detection range 13A for detection ofuser's fingertip position, set further upward relative to the surface ofthe image forming optical system 12. In FIG. 24, the limit to the rangeover which images can be captured is indicated by a dotted line 13 aabove the image-capturing device 18 and the detection range 13A isdefined by the detection limit 13 a and the surface of theimage-capturing optical system 12. In variations 8, too, the midairimage 30 and the detection reference 40 are set inside the detectionrange 13A, as in the first embodiment and variations 1 through 7described earlier. It is to be noted that while the detection reference40 in FIG. 24 is set further upward relative to the midair image 30, itmay instead be set further downward relative to the midair image 30 orin alignment with the position of the midair image 30, as long as it isset within the detection range 13A. A range other than the area set asthe detection reference 40 within the detection range 13A is referred toas outside a detection reference 41 in the description of variation 8.It is to be noted that instead of setting the detection range 13A bydefining the limit to the range over which an image can be captured withthe image-capturing device 18, the detection range 13A may be set as arange made up with part of the range over which an image can be capturedby taking off, for instance, predetermined ranges at the left and theright ends in FIG. 24.

The display device 1 in variation 8 described above includes anoperation detector configured with the image-capturing device 18 insteadof the capacitive panel 13. However, the display device 1 may includeboth the operation detector 13 and the image-capturing device 18. Insuch a case, the detection range 13A of the operation detector 13 shownin FIG. 3 may be divided into, for instance, two parts, i.e., a top partand a bottom part, so as to form a lower detection range (a detectionrange closer to the display unit 11) and an upper detection range (adetection range further away from the display unit 11), and the lowerdetection range and the upper detection range may be respectivelydesignated as the detection range for the capacitive panel 13 and thedetection range for the image-capturing device 18. In thisconfiguration, as the user moves his finger downward in order to performan operation at the display position, the image-capturing device 18detects the first half of the descending movement of the finger and thecapacitive panel 13 detects the second half of the descending movementof the finger. Generally speaking, highly accurate detection is enabledvia the capacitive panel 13 over a range set above and in closeproximity to the display unit 13, whereas it may not always be possibleto capture an image with the image-capturing device 18 over a range setabove and in very close proximity to the display unit 13. For thisreason, it is desirable to assign different detection ranges to thecapacitive panel 13 and the image-capturing device 18, as describedabove. It is to be noted that the detection range 13A does not need tobe divided into two equal parts along the up/down direction and instead,it may be divided into parts that are not equal. An operation detector13 configured with another device, such as a proximity sensor, insteadof the capacitive panel 13 or the image-capturing device 18, may beused. This means that detection ranges formed by dividing the detectionrange 13A may be assigned to various operation detectors 13.

The velocity/acceleration detection unit 206 shown in FIG. 9 is alsocapable of calculating the velocity and the acceleration with which thefinger moves based on a captured image provided by the image-capturingdevice 18 in FIG. 23. Accordingly, in correspondence to each of theupper and lower detection ranges formed by dividing the detection range13A, the finger movement velocity or the finger movement accelerationmay be calculated and the stop position predicting unit 207 may predictthe reach position of the finger.

It is to be noted that while the display device 1 in the firstembodiment and its variations 1 through 7 described above includes atleast the control unit 20, the display unit 11 and the operationdetector 13, the present invention may instead be adopted in a detectiondevice configured with the control unit 20 alone or a detection deviceconfigured with the control unit 20 and the operation detector 13. Thecontrol unit 20 may include, at least, the calibration unit 203 and thedetection reference control unit 204. A structural element may be addedas needed in order to realize the various advantages described inreference to the first embodiment or any of variations 1 through 7.

Second Embodiment

In reference to drawings, a display device 1 achieved in the secondembodiment will be described. The second embodiment will be described inreference to an example in which the display device 1 is built into aportable telephone. It is to be noted that the display device achievedin this embodiment may be built into any of various electronicapparatuses including a portable information terminal device such as atablet terminal or a wristwatch terminal, a personal computer, a musicplayer, a landline telephone and a wearable apparatus, instead of aportable telephone.

The display device 1 achieved in the embodiment, similar to the displaydevice 1 shown in FIG. 1, includes main structural elements shown in theblock diagram presented in FIG. 25. Namely, it includes a control unit20, and a display unit 11 and an operation detector 13 controlled by thecontrol unit 20. The control unit 20 includes an image generation unit201, a display control unit 202, a calibration unit 203, a detectionreference control unit 204, a storage unit 205 and a user informationanalysis unit 210.

Since the main structure of the control unit 20 is similar to that inthe display device 1 in the first embodiment except that the controlunit 20 in this embodiment includes the user information analysis unit210, the following explanation will focus on the structural feature thatdifferentiates the control unit 20 in this embodiment from that in thefirst embodiment. The detection reference control unit 204 first setsthe detection reference at the initial position and then changes thedetection reference based on the results of calibration processing to bedescribed later. The user information analysis unit 210 analyzesinformation relating to the user input thereto. Based upon informationinput thereto from the user information analysis unit 210 during thecalibration processing, the detection reference control unit 204 changesthe detection reference.

Next, in reference to the flowchart presented in FIG. 26, thecalibration processing executed in the display device 1 in theembodiment will be described. It is to be noted that the flowchart inFIG. 26 shows the processing executed in steps S201 through S207 anddoes not show the processing executed in subsequent steps. Theprocessing executed in step S207 and subsequent steps is similar to theprocessing executed in step S109 and subsequent steps in the flowchartpresented in FIG. 11. After the display device 1 is started up, theprocessing in the flowchart presented in FIG. 26 is executed by thecontrol unit 20 based on a program. The program is stored in the storageunit 205.

In step S201, a decision is made as to whether or not the user hasoperated a user information input mode operation button. When anaffirmative decision is made in step S201, i.e., when it is decided thatthe user has selected a user information input mode, the operationproceeds to step S202. When a negative decision is made in step S201,i.e., when it is decided that the user has not the selected the userinformation input mode, the operation proceeds to step S206. In stepS202, the user information input mode starts and then the operationproceeds to step S203. In step S203, a decision is made as to whether ornot an input of user information has ended. This decision may be made byverifying whether or not the user has operated a button via which a userinformation input end instruction is issued. When an affirmativedecision is made in step S203, i.e., when the user has issued a userinformation input end instruction, the operation proceeds to step S204.When a negative decision is made in step S203, the operation waits instandby until an affirmative decision is made.

In step S204, the user information analysis unit 210 changes the initialsetting to be taken for the detection reference 40 in the midair imageoperation mode based on the user information having been input theretoand stores the position data for the changed detection reference 40 intothe storage unit 205, before the operation proceeds to step S205. Thedetection reference 40 may be changed to, for instance, a positionfurther upward relative to the reach position 50 by a predetermineddistance d1. In step S205, the user information input mode ends, and theoperation proceeds to step S206. In step S206, the midair imageoperation mode starts.

The user information may indicate at least one of; the user's gender,age, body type (height and reach) and vision, or the user informationmay be a combination of a plurality of user characteristics such as theuser's gender, age, body type (height and arm-length) and vision. Aplurality of tables relating to the reach position 50, each compiled byusing a single factor or a combination of a plurality of factors amonggender, age, body type (height) and vision as a parameter, are stored inadvance in the storage unit 205. Based upon the type and the contents ofthe user information input thereto, the user information analysis unit210 selects an applicable table and selects the reach positioncorresponding to the user information in the table. Based upon theselected reach position 50, the detection reference control unit 204sets the detection reference 40.

Reach positions 50 stored in the tables are set so that a reach position50 closer to the operation detector 13 is selected when, for instance,the user is female rather than male, when the user is younger ratherthan older or when the user is shorter rather than taller.

It is to be noted that while a decision is made in step S201 in theflowchart presented in FIG. 26 as to whether or not the user hasoperated the user information input mode operation button, it is notalways necessary to execute this processing and instead, the operationmay shift to step S204 when the device obtains user information.

It is to be noted that the user information indicating the user'sgender, age, body type (height, reach), vision or the like may be storedin the storage unit 205 in correlation to an ID (identification code)used to identify the particular user and a password. In this case, theuser operating the display device 1 is able to set the detectionreference 40 based on the information indicating his/her gender, age,body type (height), vision or the like simply by entering the ID and thepassword. As described above, the positional relationship between thedetection reference 40 and the midair image 300 is changed by changingthe detection reference 40 for the particular user based on the userinformation that is a type of user-related information.

The user may be identified through image analysis of a captured imageobtained by capturing an image of the user with an image-capturingdevice 18 such as that described in reference to variation 8 of thefirst embodiment. In such a case, the age, the gender and the like ofthe user in the captured image may be determined through, for instance,face recognition technology of the known art. The detection referencecontrol unit 204 is then able to set the detection reference 50 based oninformation relating to the gender, age and the like of the user. Inthis case, the user does not need to enter the ID or the password.Through this process, too, the positional relationship between thedetection reference 40 and the midair image 300 can be modified bychanging the detection reference 40 for that particular user based onthe user information that is a type of user-related information.

Variation 1 of the Second Embodiment

The second embodiment allows for the following variation. Namely, theuser may enter user information at an information input device otherthan the display device 1 and the information, having been input, may betransferred to the display device 1 via an interface. User informationmay be pre-recorded in an IC card and in such a case, it is desirablethat the display device 1 or the information input device have a readfunction for card information.

It is to be noted that while the display device 1 in the secondembodiment described above includes, at least, the control unit 20, thedisplay unit 11 and the operation detector 13, the present invention mayinstead be adopted in a detection device configured with the controlunit 20 alone or a detection device configured with the control unit 20and the operation detector 13. The control unit 20 may include at leastthe calibration unit 203 and the detection reference control unit 204. Astructural element may be added as needed in order to realize thevarious advantages described in reference to the second embodiment.

Third Embodiment

In reference to drawings, a display device 1 achieved in the thirdembodiment will be described. The third embodiment will be described inreference to an example in which the display device 1 is built into aportable telephone. It is to be noted that the display device achievedin this embodiment may be built into any of various electronicapparatuses including a portable information terminal device such as atablet terminal or a wristwatch terminal, a personal computer, a musicplayer, a landline telephone and a wearable apparatus, instead of aportable telephone.

The display device 1 achieved in the embodiment, similar to the displaydevice 1 shown in FIG. 1, includes main structural elements shown in theblock diagram presented in FIG. 27. The display device 1 in theembodiment includes a control unit 20, and a display unit 11, anoperation detector 13 and an environment detection unit 19 controlled bythe control unit 20. The environment detection unit 19 detects anoperating environment of the display device 1. The control unit 20includes an image generation unit 201, a display control unit 202, acalibration unit 203, a detection reference control unit 204, a storageunit 205 and an environment analysis unit 211.

The environment analysis unit 211 determines whether or not a change inthe environment has occurred by analyzing environment information inputthereto from the environment detection unit 19, and outputs environmentchange information to the detection reference control unit 204 there hasbeen a change in the environment. The detection reference control unit204 executes detection reference calibration processing based on theenvironment change information input thereto from the environmentanalysis unit 211.

The calibration processing in this embodiment is executed concurrentlywhile midair image operation mode execution is underway. In reference tothe flowchart presented in FIG. 28, the calibration processing executedin the embodiment will be described. After the display device 1 isstarted up, the processing in the flowchart presented in FIG. 28 isexecuted by the control unit 20 based on a program. The program isstored in the storage unit 205.

In step S211, the midair image operation mode starts and then theoperation proceeds to step S212. In step S212, a midair image 30 thatincludes icons 30A for the midair image operation mode, as shown in FIG.3, is displayed and the detection reference control unit 204 sets thedetection reference 40 at the predetermined initial position before theoperation proceeds to step S213. In step S213, the environment analysisunit 211 determines whether or not there has been a change in theenvironment based on environment information relating to the operatingenvironment, detected by the environment detection unit 19. When anaffirmative decision is made in step S213, i.e., when it is decided thatthere has been a change in the environment, the operation proceeds tostep S214. When, on the other hand, a negative decision is made in stepS213, i.e., when it is decided that there has been no change in theenvironment, the operation proceeds to step S216. In step S214,environment change information is output to the detection referencecontrol unit 204, and then the operation proceeds to step S215. In stepS215, the detection reference control unit 204 changes the detectionreference for the midair image operation mode based on the environmentchange information, and then the operation proceeds to step S216.Namely, the midair image operation mode is sustained in step S216.

The environment information may indicate the temperature, the humidity,the brightness and the like. The detection reference calibrationprocessing is executed based on a change in a factor among suchenvironment factors for the following reason. When the temperature ofthe display device 1 or the temperature in the vicinity of the displaydevice 1 increases while the user operates the display device 1, afastening member (not shown) that fastens the display unit 11 and theimage forming optical system 12 together is bound to expand inside thedisplay device 1, resulting in an increase in the distance between thedisplay unit 11 and the image forming optical system 12. A temperaturechange attributable to the user may occur near the midair image 30 dueto, for instance, an increase in the temperature at the display devicecaused by the heat of the user's hand holding a hand-held displaydevice, e.g., a portable telephone. Under these circumstances, themidair image 30 is formed at a position closer to the user compared tothe image forming position assumed before the temperature increase. Thebrightness in the vicinity of the midair image 30 may change while theuser is operating the display device, and under such circumstances, themidair image 30 would appear different to the user. As a result, theuser may have a perception that the midair image 30 is further awaycompared to the midair image 30 before the brightness change occurred.The shadow of the user may darken the midair image to result in a changein the brightness in the vicinity of the midair image 30. The displayperformance of the display device 1 configured with a hand-held devicesuch as a portable telephone may be affected by a change in the ambienthumidity caused by sweat in the user's hand holding the display device.

The environment detection unit 19 may be, for instance, a temperaturesensor, a humidity sensor, a brightness sensor or the like installed inthe body 10 of the display device 1. It is to be noted that thebrightness may be measured by engaging the photometering function of thecamera.

Calibration-related information generated based on the surroundingenvironment change information indicating a change in the environmentattributable to the user will be described next. A plurality of tablesof correction values for the detection reference, each compiled by usinga single factor or a combination of factors, among changes in thetemperature and the humidity occurring inside or in the vicinity of thedisplay device 1 and a change in the brightness occurring in thevicinity of the midair image 30 as a parameter, are stored in advance inthe storage unit 205. Upon deciding that there has been a change in theenvironment, the environment analysis unit 211 selects an applicabletable corresponding to the factor manifesting the change and selects aspecific correction value for the detection reference in the selectedtable. Based upon the selected correction value, the detection referencecontrol unit 204 changes the detection reference 40. Through thisprocess, the positional relationship between the detection reference 40and the midair image 300 can be changed by changing the detectionreference 40 for the particular user based on the environment changeinformation indicating a change in the environment attributable to theuser that is a type of user-related information.

The detection output provided by the environment detection unit 19 asdescribed above may also be used when changing the detection referencein the first or second calibration processing mode in the firstembodiment or in variations 1 through 8 of the first embodiment. Namely,instead of changing the detection reference based on the reach positiontaken by the user's finger, the detection reference may be changed basedon both the reach position taken by the user's finger or the designatedposition and the detection output provided by the environment detectionunit 19 in the first or second calibration processing mode describedearlier.

It is to be noted that changes occurring in the environment are notlimited to the changes in the environment attributable to the userdescribed above, and various changes in the environment, including achange caused by sunlight filtered through a window, a change in thehumidity caused by the weather, and an increase in the temperature ofthe display device as it is sustained in the ON state, may be detected,and the positional relationship between the detection reference and themidair image may be changed by changing the detection reference based onthe detection results.

It is to be noted that while the display device 1 in the thirdembodiment described above includes at least the control unit 20, thedisplay unit 11 and the operation detector 13, the present invention mayinstead be adopted in a detection device configured with the controlunit 20 alone or a detection device configured with the control unit 20and the operation detector 13. The control unit 20 may include at leastthe calibration unit 203, the detection reference control unit 204 andthe environment analysis unit 211. A structural element may be added asneeded in order to realize the various advantages described in referenceto the third embodiment.

Fourth Embodiment

In reference to drawings, a display device 100 achieved in the fourthembodiment will be described. The display device 100 in the embodimentincludes an operation detector assuming a structure different from thatof the operation detector 13 in the first embodiment. FIG. 29 shows thedisplay device achieved in the embodiment with FIG. 29(a) schematicallyillustrating the structure of an operation detector 100 in the displaydevice 100 achieved in the fourth embodiment in a sectional view. FIG.19(b) provides a perspective of an automatic cash dispenser (ATM system)200 representing an example of an electronic apparatus with the displaydevice 100 mounted therein. The display device 100 is mounted on thefront panel, via which the user enters his pin number, a cash amount andthe like at the automatic cash dispenser 200. It is to be noted thatinstead of an automatic cash dispenser, the display device 100 may bemounted in any of a wide range of electronic apparatuses includingvarious types of ticket vending machines, at which train and bustickets, passes and the like are purchased and various types ofinformation search terminal devices installed in libraries, museums, artgalleries and the like. In order to facilitate an explanation, acoordinate system that assumes an X axis, a Y axis and a Z axis set asindicated in the figure in relation to the display device 100, is set.

As FIG. 29(a) shows, the display device 100 includes a display unit 111,an image forming optical system 112 and an operation detector 113disposed inside the body (not shown). The display unit 111 disposedinside the body, constituted with a liquid crystal element, an organicEL element or the like, includes a plurality of display pixels arrayedin a two-dimensional pattern. The display unit 111 displays an imagecorresponding to display image data under control executed by a controlunit (not shown) similar to the control unit 20 in the display device 1achieved in the first embodiment. The image forming optical system 112is disposed so as to achieve a predetermined positional relation to thedisplay unit 111. The image forming optical system 112 may be configuredby two elements, each having two types of reflective strips disposedover a uniform distance from each other so as to run parallel to eachother inside a transparent substrate, one element on top of the other.

FIG. 30 is a block diagram showing a control unit 20 and the displayunit 111 and the operation detector 113 controlled by the control unit20 in the display device 100. The display device 100 in the blockdiagram in FIG. 30 is substantially identical to the display device 1 inthe block diagram in FIG. 2, except that the structures of the displayunit 111 and the operation detector 113 are different from those of thedisplay unit 11 and the operation detector 13 in the display device 1.Namely, the control unit 20, comprising a CPU, a ROM, a RAM and thelike, includes an arithmetic operation circuit that controls variousstructural elements including the display unit 111 and the operationdetector 113 in the display device 110 based on a control program andexecutes various types of data processing. The control unit 20 includesan image generation unit 201, a display control unit 202, a calibrationunit 203, a detection reference control unit 204 and a storage unit 205.The storage unit 205 includes a nonvolatile memory where the controlprogram is stored, a storage medium where image data to be displayed atthe display unit 11 and the like are stored, and the like.

The image forming optical system 112 generates a midair image 30 thatincludes icons such as that shown in FIG. 29, by deflecting a light fluxemitted from an image displayed at the display unit 111 incorrespondence to display image data. The operation detector 113 isdisposed in the vicinity of the midair image 30 so as to surround themidair image 30. FIG. 31 shows the operation detector 113 in a planview. The operation detector 113 includes a housing 115 with a sectionthereof parallel to the XY plane forming a rectangular frame shape. Aplurality of light emitting elements 116 are disposed at two surfacesranging next to each other, among the four surfaces defining the innersurfaces of the housing 115, and a plurality of light receiving elements117 are disposed at the remaining two surfaces ranging next to eachother. The frame-shaped housing 115 in FIG. 31 includes a pair of innersurfaces ranging parallel to the ZX plane with light emitting elements116 alone disposed at an inner surface ZX 1 and light receiving elements117 alone disposed at an inner surface ZX 2. Likewise, at a pair ofinner surfaces ranging parallel to the YZ plane, light emitting elements116 alone are disposed at an inner surface YZ 1 and light receivingelements 117 alone are disposed at an inner surface YZ 2. Namely, thelight emitting elements 116 and the light receiving elements 117 aredisposed so as to face opposite each other. The light emitting elements116 may be constituted with commonly available laser elements or LEDelements. The light receiving elements 117 may be constituted withcommonly available photodiodes or photo transistors. It is to be notedthat the operation detector may be configured with lightemitting/receiving elements each constituted with a light emittingelement and a light receiving element combined so as to form anintegrated unit, and in such a case, the light emitting/receivingelements would be disposed in place of the light emitting elements andmirrors would be disposed in place of the light receiving elements.

The light emitting elements 116 and the light receiving elements 117 aredisposed in a neat array so as to achieve a 1 to 1 correspondence in astructure in which light emitted from a given light emitting element 116only enters a single light receiving element 117 that corresponds to thelight emitting element 116. A light beam emitted from a light emittingelement 116 advances within a plane parallel to the midair image I(i.e., within a plane parallel to the XY plane) and enters thecorresponding light receiving element 117. Information indicating thelight detection condition at the light receiving element 117 istransmitted to the control unit, which ascertains the detectioncondition at the light receiving element 117 in correspondence to theposition of the light receiving element 117. Thus, a group of lightpaths assuming a multi-stage two-dimensional lattice pattern paralleledto the XY plane is formed inside the housing 117. It is desirable thatthe wavelength of light emitted from the light emitting elements 116 bewithin the infrared band.

A position detector 113 is shown in a sectional view in FIG. 32. Inorder to simplify an explanation, the structure shown in FIG. 32includes light emitting elements 116 and light receiving elements 117,disposed over six stages along the Z direction. The light emittingelements 116 disposed over six stages are assigned with referencenumerals 116 a, 116 b, 116 c, 116 d, 116 e and 116 f starting on the +side along the Z direction. The light receiving elements 117 disposedover six stages are assigned with reference numerals 117 a, 117 b, 117c, 117 d, 117 e and 117 f starting on the + side along the Z direction.In this case, the position detector 113 assumes a detection rangebetween the light emitting element 116 a and the light emitting element116 f, and this detection range is equivalent to the detection range 13Ain FIG. 3, in reference to which the first embodiment has beendescribed.

The functions of the operation detector 113 are explained in referenceto FIG. 32. The display control unit 204 in the display device 100 formsa midair image 30 at a position set apart from the display device 100.The midair image 30 includes icons 30A and the position at which themidair image 30 is generated along the up/down direction is on a planealigned with the light emitting element 116 d and the correspondinglight receiving element 117 d. The detection reference control unit 204sets the detection reference 40 at a predetermined initial position. Inthis example, the detection reference 40 is set on a plane aligned withthe light emitting element 116 c and the light receiving element 117 c.It is desirable that light emitting elements 116 and light receivingelements 117 be disposed over numerous stages along the up/downdirection so as to enable fine adjustment of the positions taken for themidair image 30 and the detection reference 40.

The user moves his fingertip down toward a first icon 30A in order toperform an operation at the first icon 30A in the midair image 30, andas the fingertip reaches the detection limit of the operation detector113 (the plane aligned with the light emitting element 116 a and thelight receiving element 117 a in this example), the operation detector113 detects the approaching fingertip based on an output from the lightreceiving element 117.

As the fingertip F reaches a position indicated by a dotted line 50further upward relative to the icons 30A in the midair image 30, theuser experiences a perception of his finger, having reached an icon 30B,performing an operation and thus stops the downward movement of thefingertip F. The detection reference control unit 204 decides that thefingertip F has stopped moving downward, i.e., an operation has beenperformed at the display position of the icon 30B, when light iscontinuously detected at the light receiving element 117 c over a lengthof time equal to or greater than a predetermined time interval with nolight being detected at the light receiving elements 117 a and 117 b. Atthis time, the plane aligned with the light emitting element 116 b andthe light receiving element 117 b is designated as the reach position atwhich the fingertip F has stopped its movement and performed anoperation at the display position of the icon 30A.

Upon determining the reach decision 50, the detection reference controlunit 204 changes the position of the detection reference 40, currentlyset at the initial position, to, for instance, the reach position 50,and stores the position data for the changed detection reference 40 intothe storage unit 205 in FIG. 2. Through this process, the detectionreference 40, suitable for the particular user, is set based on thereach position 50, as in the display device 1 achieved in the firstembodiment. Namely, the plane aligned with the light emitting element116 c and the light receiving element 117 c, among the light emittingelements 116 and the light receiving elements 117 disposed over multiplestages, is selected as the initial setting for the detection reference40 and the detection reference 40 is then changed to the position inalignment with the plane aligned with, for instance, the light emittingelement 116 b and the light receiving element 117 b based on the reachposition through calibration processing, so as to change the positionalrelationship between the detection reference 40 and the display positionof the midair image 30. It is to be noted that the position of thedetection reference 40 may be changed to the reach position 50 throughthe calibration processing, i.e., the position of the detectionreference 40 may be changed to the plane that is aligned with the lightemitting element 116 b and the light receiving element 117 c among theplurality of light emitting elements 116 and the light receivingelements 117. The detection reference set at the initial position may bechanged based on the reach position so as to take a position furtherupward relative to the reach position or a position further downwardrelative to the reach position.

The detection reference may be also altered to a detection referenceassuming a depth d2 as illustrated in FIG. 21(c). Such a detectionreference may be set by selecting the light emitting element 116 a andthe light receiving element 117 a located further upward relative to thereach position 50, designating the plane aligned with the light emittingelement 116 a and the light receiving element 117 a as an upper plane401, selecting the light emitting element 116 c and the light receivingelement 117 c located further downward relative to the reach position50, and designating the plane aligned with the light emitting element116 c and the light receiving element 117 c as a lower plane 402, i.e.,by setting the upper plane 401 in alignment with the plane aligned witha pair of a light emitting element 116 and a light receiving element117, among a plurality of pairs each made up with a light emittingelement 116 and a light receiving element 117, and setting the lowerplane 402 in alignment with the plane aligned with another pair of alight emitting element 116 and a light receiving element 117.

In the embodiment described above, the position of the detectionreference can be changed by selecting a pair of a light emitting element116 and a light receiving element 117 or a plurality of pairs, each madeup with a light emitting element 116 and a light receiving element 117based on the reach position and thus selecting a specific detectionreference among a plurality of detection references that can be set incorrespondence to the plurality of light emitting elements 116 and theplurality of light receiving elements 117.

As described above, while the display unit 111 and the operationdetector 113 in the display device 100 assume structures different fromthose in the display unit 11 and the operation detector 13 in thedisplay device 1, the detection reference 40 can be set through asimilar procedure. This means that the first calibration processing andthe second calibration processing can be executed at the display device100 achieved in the fourth embodiment through procedures similar tothose described in reference to the flowcharts presented in FIG. 6 andFIG. 8. The display device 100 in the fourth embodiment may be adoptedin any of the numerous variations described earlier.

It is to be noted that the display device 100 may include an actuatorand an encoder so as to allow a light emitting element 116 and a lightreceiving element 117 to move by a miniscule distance along the Zdirection. For instance, in order to change the detection reference 42to a position set apart from the reach position 50 by a distance d1, thelight emitting element 116 and the light receiving element 117 disposedat a position closest to the point set apart from the reach position 50by the distance d1 are selected. Based upon the difference between theposition at which the selected light emitting element 116 and lightreceiving element 117 are disposed and the point set apart from thereach position 50 by the distance d1, the light emitting element 116 andthe light receiving element 117 are displaced via the actuator for fineadjustment of the position of the light emitting element 116 and thelight receiving element 117. Namely, through the fine adjustment of theposition taken by the light emitting element 116 and the light receivingelement 117, the detection reference 42 can also be changed to aposition closer to the point set apart from the reach position 50 by thedistance d1.

Variation 1 of the Fourth Embodiment

The fourth embodiment allows for the following variation. The operationdetector 113 in the display device 100 achieved in the fourth embodimentincludes the light emitting elements 116 and the light receivingelements 117 disposed in a two-dimensional array over multiple stagesset one after another along the Z direction. However, the light emittingelements 116 and the light receiving elements 117 arrayed in atwo-dimensional pattern in the embodiment may instead be disposed at asingle stage. FIG. 33 shows a display device 100 equipped with such anoperation detector 113′. At a frame-shaped housing 115′ of the operationdetector 113′, a plurality of light emitting elements 116 are disposedin a single row, running parallel to the XY plane, at two the surfacesranging next to each other, among the four surfaces forming the innersurfaces of the frame-shaped housing 115′ and a plurality of lightreceiving elements 117 are disposed in a single row running parallel tothe XY plane, at the two remaining surfaces set next to each other. Inother words, the operation detector 113′ assumes a single-stagestructure, instead of the six-stage structure adopted in the operationdetector 113 described in reference to FIG. 32. The housing 115′ is ableto move reciprocally along the Z direction over predetermined cycles(e.g., 10 cycles/sec) via an actuator 119 connected thereto. The currentposition of the housing 115′ is detected by a position detection sensorsuch as an encoder (not shown) built into the actuator 119. In thiscase, a specific position falling within the range over which thehousing 115′ can move reciprocally is set for the detection reference40.

In reference to FIG. 32, the detection reference calibration processingexecuted in the display device 100 equipped with the operation detector113′ will be described. The user, wishing to perform an operation at thedisplay position of an icon 30A in the midair image 30, moves hisfingertip down toward the midair image 30. When the position of thefingertip is within the range of movement of the housing 115′, lightemitted from a light emitting element 116 is blocked by the user'sfinger and thus does not reach the corresponding light receiving element117. The position at which the light is blocked by the user's finger andthus stops traveling toward the light receiving element 117 is detectedvia the encoder as the user's fingertip position. The user moves hisfingertip further down toward the midair image 30 in order to perform anoperation at the display position of the icon 30A included in the midairimage 30. When the user perceives that the fingertip has reached theicon 30A and is performing an operation at the display position of theicon 30A, he stops moving the fingertip. The control unit 20 decidesthat the user's fingertip has become still if, for instance, theposition at which the light from the light emitting element 116 stopstraveling toward the light receiving element 117 remains substantiallyconstant during a single reciprocal movement of the housing 115′. Atthis time, the position at which the user's fingertip has become stillis designated as the reach position and the position of the detectionreference 40 is set based on the reach position thus designated. Aflowchart of the processing executed in this variation will besubstantially identical to that presented in FIG. 6.

It is to be noted that while the display device 1 in the fourthembodiment and in variation 1 described above includes at least thecontrol unit 20, the display unit 111 and the operation detector 113,the present invention may instead be adopted in a detection deviceconfigured with the control unit 20 alone or a detection deviceconfigured with the control unit 20 and the operation detector 113. Thecontrol unit 20 may include at least the calibration unit 203 and thedetection reference control unit 204. A structural element may be addedas needed in order to realize the various advantages described inreference to the fourth embodiment or variation 1.

In the fourth embodiment, the position of the user's fingertip isdetected via an operation detector configured with light emittingelements and light receiving elements. However, the present invention isnot limited to this example and may be adopted in conjunction with anoperation detection unit configured with an image-capturing unit. Forinstance, an image-capturing unit configured with a camera may bemounted at the display device so as to execute calibration processing tocalibrate the detection reference 40 based on information obtained bydetecting movement of the user's fingertip via the camera. FIG. 34 showsa display device 100′ that includes a display unit 111 and an imageforming optical system 112 similar to those in the display device 100described in reference to the fourth embodiment. The display device 100′is distinguishable from the display device 100 in that it includes animage-capturing device (e.g., a digital camera) 118 in place of theoperation detector 113. The position of the user's finger is ascertainedvia the image-capturing device 118 in the display device 100′. It isdesirable that the image-capturing device 118 include a wide-angle lensso as to cover the entire midair image 30, and such a lens may be afisheye lens. The display device may include a plurality ofimage-capturing devices (e.g., two image-capturing devices) and theposition of the user's fingertip may be detected based on capturedimages provided from the plurality of image-capturing devices.

In the first through fourth embodiments and their variations, control isexecuted so as to change the positional relationship between thedetection reference 40 and the midair image 30 (or an icon 300A or thelike) by moving the position of the detection reference 40. As analternative, the positional relationship between the detection reference40 and the midair image 30 may be changed by moving the midair image 30.The positional relationship between the detection reference 40 and themidair image 30 may be also changed by moving both the detectionreference 40 and the midair image 30.

Fifth Embodiment

While the positional relationship between the detection reference andthe display position of the midair image is changed by controlling orchanging the detection reference through calibration processing in theembodiments and the variations thereof described earlier, the positionalrelationship between the detection reference and the display position ofthe midair image may be changed by changing the midair image displayposition through calibration processing, as in the fifth embodiment tobe described next.

FIG. 35 and FIG. 36 show the display device achieved in the fifthembodiment. As does the display device in the first embodiment, thedisplay device 1 achieved in the fifth embodiment comprises a body 10having a built-in control unit 20 disposed thereat, a display unit 11,an image forming optical system 12 and an operation detector 13, asshown in FIG. 35. It also includes an image generation unit 201, adisplay control unit 202, a calibration unit 203, a detection referencecontrol unit 204 and a storage unit 205, as shown in FIG. 36. Inaddition to the structural elements listed above, the display device 1in the fifth embodiment includes a display position change unit 500 anda display position control unit 220.

The display position change unit 500, which includes a drive unit suchas a motor or an actuator, moves the image forming optical system 12along the optical axis of the image forming optical system 12, asindicated by the arrow, so as to change the display position of a midairimage 30 formed via the image forming optical system 12 by moving italong the Z axis, i.e., along the optical axis. The midair image 30 ismoved upward, further away from the display unit 11, by moving the imageforming optical system 12 downward, closer to the display unit 11,whereas the midair image 30 is moved downward, closer to the displayunit 11 by moving the image forming optical system 12 upward, furtheraway from the display unit 11. It is to be noted that the displayposition change unit 500 may move the display position of the midairimage 30 for change by moving the display unit 11 along the optical axisof the image forming optical system 12 instead of moving the imageforming optical system 12.

While the display unit 11, the image forming optical system 12 and theoperation detector 13 may be structurally identical to the display unit11, the image forming optical system 12 and the operation detector 13 inthe first embodiment shown in FIG. 1, the image forming optical system12 or the display unit 11 is structured so as to be able to move alongthe optical axis of the image forming optical system 12.

It is to be noted that while the following explanation is provided byassuming that the display position of the midair image 30 formed by theimage forming optical system 12 is moved along the Z axis, i.e., alongthe optical axis, for change, by moving the image forming optical system12 along the optical axis of the image forming optical system 12 via adrive unit such as a motor or an actuator, the present invention is notlimited to this example, and the display position control unit 220 mayinstead control the display unit 11 so as to change the display positionof the midair image 30 along the depth-wise direction by displaying adisplay image to be viewed with the right eye and a display image to beviewed with the left eye, which assumes parallax relative to the imageto be viewed with the right eye.

The image generation unit 201, the display control unit 202, thecalibration unit 203, the detection reference control unit 204 and thestorage unit 205 fulfill functions identical to those of the imagegeneration unit 201, the display control unit 202, the calibration unit203, the detection reference control unit 204 and the storage unit 205in the first embodiment shown in FIG. 1.

As described above, the control unit 20 includes the display positioncontrol unit 206 and the display position control unit 220 causes thedisplay position change unit 500 to change the display position of themidair image 30 by calculating or determining the extent to which themidair image 30 is to move based on the finger reach position or adesignated position, detected or determined in the calibrationprocessing mode.

Operations executed in the display device achieved in the fifthembodiment of the present invention will be explained next. The midairimage operation mode is executed as in the display device in the firstembodiment. Namely, as the midair image operation mode is started up,the midair image 30 for the midair image operation mode shown in FIG.3(a) is displayed via the image forming optical system 12 and thedetection reference 40 is set at a predetermined initial position by thedetection reference control unit 204. As the user's finger movesdownward in order to perform an operation at the display position of anicon 30A in the midair image 30, the operation detector 13 detects thedescending movement of the finger. Based upon the detection outputprovided by the operation detector 13, the detection reference controlunit 204 decides that the finger has reached the position of thedetection reference 40, and once this decision is made, a functioncorresponding to the icon 30A having been operated is executed. Forinstance, the display content in the midair image 30 may be switched.

As the first calibration processing mode is executed, the midair image300 for the calibration processing shown in FIG. 4 is formed via thedisplay control unit 202, the display unit 11 and the image formingoptical system 12 and the detection reference 40 is set at an initialposition near the midair image 300 by the detection reference controlunit 204. As the user's finger moves downward in order to operate anicon 300A in the midair image 300, the operation detector 13 detects thedescending movement of the finger. Based upon the detection outputprovided by the operation detector 13, the detection reference controlunit 204 determines the reach position for the finger. Thisdecision-making may be executed through any of the methods described inreference to the first embodiment and variations 1 and 2 of the firstembodiment. Based upon the finger reach position 50, the displayposition control unit 206 causes the display position change unit 500 tomove the position of the midair image 300 along the optical axis of theimage forming optical system 12.

It is to be noted that the display control unit 202, the display unit 11and the image forming optical system 12 may form any of the midairimages 300 displayed for purposes of calibration processing as shown inFIG. 12, FIG. 15 and FIG. 18, and in such a case, the detectionreference control unit 204 determines a designated position 50Aindicated with the finger based on the detection output provided by theoperation detector 13. The display position control unit 220 then causesthe display position change unit 500 to move the position of the midairimage 300 along the optical axis of the image forming optical system 12based on the designated position 50A. Once the display position of themidair image 300 is changed as described above, the first calibrationprocessing ends and in the subsequent midair image operation mode, themidair image 30 for the midair image operation mode is displayed at thechanged display position.

The display position of the midair image 300 is moved by the displayposition control unit 220 and the display position change unit 500 asdescribed below. Namely, when the finger reach position 50 or thedesignated position 50A is further upward relative to the detectionreference 40, as shown in FIG. 37(a), the display position control unit220 and the display position change unit 500 calculate a distance ΔHbetween the reach position 50 or the designated position 50A and thedetection reference 40 and moves the midair image 300 to displayposition 300 indicated by the dotted line, located further downward bythe distance ΔH. The midair image 300 displayed in space may not alwaysassure good visibility, and the display position of the midair image 300may be perceived differently from one user to another. In the examplepresented in FIG. 37(a), the user perceives that the display position ofthe midair image 300 is higher than its actual position. For thisreason, the reach position 50 or the designated position 50A for thisparticular user is further upward relative to the display position ofthe midair image 300. Accordingly, the display position of the midairimage 300 is moved downward by the distance ΔH in order to enabledetection of an operation by the user at the display position of themidair image 300. As a result, the user performs an operation at thedisplay position of the midair image 300 having been moved downward, andthe reach position 50 or the designated position 50A is thus likelymoved downward. With the reach position 50 or the designated position50A changed to a point further downward so as to reach the detectionreference, it becomes possible to detect an operation by the user at thedisplay position of the midair image 300. By changing the displayposition of the midair image 300 as described above, an operation by theuser at the display position of the midair image 30 can be detected atthe detection reference 40.

When the finger reach position 50 or the designated position 50A isfurther downward relative to the detection reference 40, as shown inFIG. 37(b), the display position control unit 220 and the displayposition change unit 500 calculate a distance ΔH between the reachposition 50 or the designated position 50A and the detection reference40 and moves the display position of the midair image 300 to a displayposition 300 indicated by the dotted line, located further upward by thedistance ΔH.

When the finger reach position 50 or the designated position 50A is inalignment with the detection reference 40 or is in the vicinity of thedetection reference 40, the display position control unit 220 and thedisplay position change unit 500 does not move the display position ofthe midair image 300.

It is to be noted that while the display position control unit 220 andthe display position change unit 500 move the display position of themidair image 300 downward when the reach position 50 or the designatedposition 50A is further upward relative to the detection reference 40and move the display position of the midair image 300 upward when thereach position 50 or the designated position 50A is further downwardrelative to the detection reference 40, it is not necessary to preciselymatch the extent of the movement with the distance ΔH between the reachposition 50 or designated position 50A and the detection reference 40and instead, the display position may be moved by an extent greater orsmaller than the distance ΔH, as has been explained in reference to thefirst embodiment.

As an example of a method that may be adopted when calculating theextent of midair image movement, numerous user's may be asked toparticipate in advance calibration processing in order to ascertain thesuitable extent of movement of the midair image 300 that affords eachuser smooth midair image operation by moving the display position of themidair image 300 by different extents relative to the distance ΔHbetween the reach position or the designated position and the detectionreference, and statistical processing may be executed on these extentsof movement of the midair image 300 to determine the extent of movementfor the midair image relative to the distance ΔH.

The extent of midair image movement through the statistical processingmay be, for example, a common value for all users, or different values,each corresponding to a specific user age group or a specific gender. Itis to be noted that the method of determining the extent of midair imagemovement through the statistical processing described above may also beadopted when determining the extent to which the detection reference isto move for change based on the reach position or the designatedposition in the first embodiment described earlier.

An example in which the calibration processing described above isexecuted in the first calibration processing mode will be explained inreference to the flowchart presented in FIG. 38. It is to be noted thatthe flowchart in FIG. 38 shows the processing executed in steps S301through S308 and does not show the processing executed in subsequentsteps. The processing executed in step S308 and subsequent steps issimilar to the processing executed in step S9 and subsequent steps inthe flowchart presented in FIG. 6.

The processing executed in steps S301 through S305 is similar to theprocessing executed in steps S1 through S5 in the flowchart presented inFIG. 6. In step S306, the display position control unit 206 changes thedisplay position of the midair image 300. Namely, the display positioncontrol unit 206 causes the display position change unit 500 to move thedisplay position of the midair image 300 along the optical axis of theimage forming optical system 12 based on the finger reach position 50,and then the operation proceeds to step S307. In step S307, the firstcalibration processing mode ends and then the operation proceeds to stepS308. In step S308, the midair image operation mode starts. It is to benoted that when the midair image displayed in step S303 is any of themidair images 300 shown in FIG. 12, FIG. 15 and FIG. 18, the designatedposition 50A should be determined in step S305 and the display positionof the midair image 300 should be changed based on the designatedposition 50A in step S306.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, it may be alsoadopted in the second calibration processing mode.

The display device achieved in the fifth embodiment as described above,which changes the positional relationship between the midair imagedisplay position and the detection reference by changing the displayposition of the midair image based on the reach position or thedesignated position through the calibration processing, is capable ofachieving a suitable positional relationship for the midair imagedisplay position and the detection reference suited for the operationcharacteristics of a specific user.

If the detection reference changed through calibration processing islikely to be set outside the detection range 13A of the operationdetector 13 shown in FIG. 3 or near the upper limit or the lower limitof the detection range 13A, the midair image, instead of the detectionreference, may be moved through calibration processing so as to avertsuch an eventuality.

Variation 1 of the Fifth Embodiment

Next, variation 1 of the display device achieved in the fifth embodimentwill be described.

While the display device in the fifth embodiment changes the midairimage display position based on the reach position or the designatedposition through the calibration processing, the display positioncontrol unit 220 and the display position change unit 500 change themidair image display position, and the detection reference control unit204 changes the position of the detection reference based on the reachposition or the designated position in the calibration processingexecuted in variation 1 of the display device achieved in the fifthembodiment. Through change of both the display position of the midairimage and the position of the detection reference, a suitable positionalrelationship suited for the operation characteristics of a specificuser, can be achieved. When it is difficult to accurately move themidair image to the suitable display position determined based on thereach position or the designated position via the display positionchange unit 500, the midair image display position may first be roughlyadjusted by the display position change unit 500 and then the detectionreference may be fine-adjusted by the detection reference control unit204, so as to achieve a suitable positional relationship for the midairimage display position and the detection reference.

Variation 2 of the Fifth Embodiment

Variation 2 of the display device achieved in the fifth embodiment willbe described below. When the display position control unit 220 and thedisplay position change unit 500 in the display device in variation 2moves the midair image display position, the midair image display iscontrolled so that it fades out and then fades in during the period oftime elapsing between the movement start and the movement end. Namely,at the start of midair image movement, the display luminance isgradually lowered and then, toward the end of the midair image movement,the display luminance is gradually raised. The movement of the midairimage during the calibration processing may look jarring to the user.Accordingly, the display luminance is gradually reduced as the midairimage begins to move so as to make the midair image movement lessvisible to the user and reduce the discomfort that may otherwise beexperienced by the user.

The display control unit 202 may lower the display luminance or thecontrast of the moving midair image, flash the midair image display atlowered luminance or contrast, or may even hide the midair image. Byrendering the movement of the midair image, achieved via the displayposition change unit 500 less noticeable, i.e., less visible, throughthese measures the user experience will be improved. As an alternative,a display mode that renders the midair image more noticeable as it movesmay be adopted. In the display mode for rendering the midair image morenoticeable, the display luminance or the contrast of the moving midairimage may be raised or the midair image display may be flashed. In thedisplay mode for rendering the midair image itself more noticeable, themovement of the midair image can be rendered less noticeable. In otherwords, the user's attention will be focused on the midair image itselfrather than on the movement of the midair image. Under suchcircumstances, the user will not be bothered or distracted by themovement of the midair image.

The midair image display mode is switched for midair image movement asdescribed above during the processing executed in step S306 in theflowchart presented in FIG. 38.

Instead of rendering the entire midair image display less noticeable ormore noticeable during the movement of the midair image, part of themidair image, e.g., the icon for the calibration processing, may berendered less noticeable or more noticeable. The user may choose as anoption whether or not to render the midair image movement morenoticeable as described above.

While the calibration processing is underway, the movement of the midairimage, achieved via the display position change unit 500, may berendered more noticeable so as to enable the user to be aware of themidair image movement. The display control unit 202 may raise thedisplay luminance or the contrast of the moving midair image or mayflash the midair image display. While the midair image movement isrendered less noticeable in the explanation provided earlier, theposition to which the midair image moves can be indicated clearly byrendering the movement of the midair image more noticeable to the user.

The midair image display luminance is switched for midair image movementas described above during the processing executed in step S306 in theflowchart presented in FIG. 38.

Variation 3 of the Fifth Embodiment

Variation 3 of the display device 1 achieved in the fifth embodimentwill be described next. The display device 1 achieved in variation 3starts midair image display position change in response to an operationby the user during the calibration processing. As the operation by theuser ends, the display position control unit 220 controls the displayposition change unit 500 so as to start change of the midair imagedisplay position.

An example in which the calibration processing described above isexecuted in the first calibration processing mode will be explained inreference to the flowchart presented in FIG. 39. It is to be noted thatthe flowchart in FIG. 39 shows the processing executed in steps S311through S319 and does not show the processing executed in subsequentsteps. The processing executed in step S319 and subsequent steps issimilar to the processing executed in step S9 and subsequent steps inthe flowchart presented in FIG. 6.

The processing executed in steps S311 through S315 is similar to theprocessing executed in steps S301 through S305 in the flowchartpresented in FIG. 38. In step S316, a decision is made as to whether ornot the operation by the user has ended. When an affirmative decision ismade in step S316, i.e., when it is decided that the operation by theuser has ended, the operation proceeds to step S317. When a negativedecision is made in step S316, the operation returns to step S314. Theprocessing executed in steps S317 through S319 is similar to theprocessing executed in steps S306 through S308 in the flowchartpresented in FIG. 38.

It is to be noted that the processing in step S316, through which adecision is made as to whether or not the operation by the user hasended, is executed in order to determine whether or not to change themidair image display position. Accordingly, the operation by the usermay be judged to have ended when the reach position or the designatedposition is determined or when a specific gesture signaling displayposition change (a gesture such as the user's hand forming the “paper”sign switching to the “stone” sign) is detected after the reach positionor the designated position is determined. As an alternative, theoperation by the user may be judged to have ended when the user's fingeris detected to press down a display position change button displayed inthe midair image after the reach position or the designated position isdetermined.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, it may be alsoadopted in the second calibration processing mode.

Variation 4 of Fifth Embodiment

Variation 4 of the display device 1 achieved in the fifth embodimentwill be described next. The user of the display device 1 in variation 4signals the timing with which change of the midair image displayposition starts with his voice during calibration processing. FIG. 40 isa block diagram showing a display unit 11 and an operation detector 13controlled by a control unit 20 in the display device 1 achieved invariation 4. The display device 1 includes the sound collector 14 invariation 6 of the first embodiment shown in FIG. 17 with a sounddetection unit 208 installed in the control unit 20.

The display device 1 determines the reach position 50 as in the firstembodiment. The display control unit 202 brings up a superimposeddisplay of a message “execute calibration. Please say “yes”” at acalibration icon 300F in the midair image 300, as shown in FIG. 41. Asthe user, prompted by the message displayed at the calibration icon300F, says “yes”, the sound collector 14 collects the sound and outputsthe sound as audio data to the sound detector 208. When the sounddetector 208 decides that the audio data corresponds to “yes”, thedisplay position control unit 220 controls the display position changeunit 500 so as to change the display position of the midair image 300.The change of the midair image display position described above isexecuted by making a decision in step S316 in the flowchart presented inFIG. 39, in reference to which variation 3 of the fifth embodiment hasbeen described, as to whether or not the user has said “yes” instead ofmaking a decision as to whether or not the operation by the user hasended and proceeding to step S317 upon making an affirmative decision instep S316, i.e., upon deciding that the user has said “yes”.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, it may be alsoadopted in the second calibration processing mode.

The display device 1 does not need to include the sound collector 14 andthe sound detection unit 208 in such a configuration may execute sounddetection by using audio data input from an external sound collectingdevice via either a wireless means or a wired means.

It is to be also noted that after the detection reference control unit204 determines the finger reach position or the designated position, themidair image movement does not start until the user says “yes” and themidair image starts moving when the user's voice saying “yes” isdetected. This means that the user may repeatedly perform an operationat the midair image display position many times before he says “yes”. Insuch a case, the midair image should be moved when the user says “yes”based on an average value representing the plurality of reach positionsor designated positions, e.g., the arithmetic mean or the geometric meanof the plurality of reach positions or designated positions, a median ofthe plurality of reach positions 50, or the most recent reach positionor designated position among the plurality of reach positions ordesignated positions.

Variation 5 of the Fifth Embodiment

Variation 5 of the display device achieved in the fifth embodiment willbe described next. The display device 1 in variation 5 suspends midairimage movement while the user is viewing the midair image and moves themidair image as the user takes his eyes away from the midair image.Accordingly, the display device 1 includes an image-capturing deviceconfigured with a camera or the like, as in variation 8 of the firstembodiment, images of the user are captured via the image-capturingdevice while the calibration processing is underway, the control unit 20analyzes the image data expressing the captured images and judges thedirection along which the user's face or body is turned based on theanalysis results in order to determine whether or not the user isviewing the midair image. The display position control unit 220 and thedisplay position change unit 500 move the midair image when the user isnot looking at the midair image. The movement of the midair image duringthe calibration processing may look jarring to the user. Accordingly,the midair image is made to move when the user takes his eyes off themidair image, and as a result, the user does not need to see themovement of the midair image, which reduces the discomfort of the user.

Instead of an image-capturing device, the display device 1 may include aline-of-sight detector that detects the user's line of sight, and basedon a detection output provided by the line-of-sight detector, thedisplay position control unit 220 and the display position change unit500 may move the midair image when the user is not looking at the midairimage, i.e., when the user's line of sight does not extend toward themidair image. The change of the midair image display position describedabove is executed by making a decision in step S316 in the flowchartpresented in FIG. 39, in reference to which variation 3 of the fifthembodiment has been described, as to whether or not the user is lookingat the midair image instead of making a decision as to whether or notthe operation by the user has ended and proceeding to step S317 uponmaking an affirmative decision in step S316 when it is decided that theuser is looking at the midair image.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, it may be alsoadopted in the second calibration processing mode.

It is to be also noted that the line-of-sight detector or theimage-capturing device described above does not need to be installed inthe display device 1. The line-of-sight detector may be installedoutside the display device 1 and may transmit line-of-sight detectionresults to the display device 1 through wireless communication or via acable. The image-capturing device may be installed outside the displaydevice 1 and may transmit image-capturing data to the display device 1through wireless communication or via a cable

It is to be further noted that while the midair image display positionis changed when it is decided that the user is looking at the midairimage, the display position control unit 220 and the display positionchange unit 500 may instead execute control so as to change the midairimage display position when it is decided that the user is looking atthe midair image. In the latter case, the user, looking at the movingmidair image is able to sense the extent to which the midair image hasmoved and thus, the user can be prompted to alter the operatingposition.

It is to be noted that while control is executed so as to change themidair image display position when the user is not looking at the midairimage in the explanation provided above, control may instead be executedso as to change the midair image display position based on a valueindicated in user biometric information. The user's pulse rate may beobtained as such user biometric information. The user's pulse rate maybe gauged via, for instance, a pulse rate counting device worn by theuser. Then, the display position control unit 220 and the displayposition change unit 500 may execute control so as to change the midairimage display position when the user's pulse rate increases. The user'spulse rate may rise when the user, being unable to perform an operationsmoothly, becomes frustrated. In this situation, change of the midairimage display position will assure better ease of device operation forthe user.

It is to be also noted that after the detection reference control unitdetermines the finger reach position or the designated position, themidair image movement does not start while the user is looking at themidair image and the midair image starts moving when the user is notlooking at the midair image is detected in the explanation providedabove. This means that the user may repeatedly perform an operation atthe midair image display position many times before he stops looking atthe midair image. In such a case, the midair image should be moved whenthe user looks away from the midair image based on an average valuerepresenting the plurality of reach positions or designated positions,e.g., the arithmetic mean or the geometric mean of the plurality ofreach positions or designated positions, a median of the plurality ofreach positions 50, or the most recent reach position or designatedposition among the plurality of reach positions or designated positions.

Variation 6 of the Fifth Embodiment

Variation 6 of the display device achieved in the fifth embodiment willbe described next. The display device 1 achieved in variation 6 iscapable of altering the velocity of the midair image movement during thecalibration processing. The display device 1 is capable of moving themidair image at very high speed for at low speed. The display positioncontrol unit 220 and the display position change unit 500 move themidair image at very high speed equal to or higher than the firstpredetermined value or at low speed equal to or lower than the secondpredetermined value smaller than the first predetermined value. The useris not able to easily see the movement of the midair image when themidair image moves at very high speed or at low speed as describedabove. The user may be allowed to choose whether to move the midairimage at very high speed or at low speed via, for instance, a selectorswitch. Under the control executed by the display position control unit220 and the display position change unit 500, as described above, theuser is not able to easily see the movement of the midair image displayposition. In other words, since the user cannot see the movement of themidair image, he will not find it jarring. When the midair image displayposition needs to move by a large distance for change, the user may findthe change of the midair image display position too noticeable andaccordingly, the first predetermined value and the second predeterminedvalue may be changed based on the distance by which the display positionneeds to be moved. For instance, when the midair image display positionneeds to move by an extent equal to or greater than a predetermineddistance, the first predetermined value may be raised and the secondpredetermined value may be lowered, in comparison to the values takenfor the first predetermined value and the second predetermined valuewhen the midair image display position needs to move by an extent equalto or less than the predetermined distance.

It is to be noted that while the display device 1 in the fifthembodiment and variations 1 through 6 thereof includes at least thecontrol unit 20, the display unit 11 and the operation detector 13, thepresent invention may instead be adopted in a control device configuredwith the control unit 20 alone or a control device configured with thecontrol unit 20 and the operation detector 13. The control unit 20 mayinclude at least the calibration unit 203 and the display positioncontrol unit 220. A structural element may be added as needed in orderto realize the various advantages described in reference to the fifthembodiment or variations 1 through 6 thereof

Sixth Embodiment

The display device achieved in the sixth embodiment will be described inreference to FIG. 42. The display device to be described below assumes astructure identical to that of the display device achieved in the fifthembodiment described in reference to FIG. 35 and FIG. 36. It differsfrom the display device in the fifth embodiment in that a firstdetection reference 40 a and a second detection reference 40 b, assuminginitial positions on the two sides of the midair image 30, are set asshown in FIG. 42. It is to be noted that in the example presented inFIG. 42, the midair image 30 is set so as to take a position halfwaybetween the first and second detection references 40 a and 40 b, i.e.,so that the distance between the midair image 30 and the first detectionreference 40 a is equal to the distance between the midair image 30 andthe second detection reference 40 b. However, it is not always necessaryto set the distance between the midair image 30 and the first detectionreference 40 a and the distance between the midair image 30 and thesecond detection reference 40 b equal to each other. An icon 30A isdisplayed in the midair image 30.

As the finger F moves down toward the icon 30A in the midair imageoperation mode, the operation detector 13 detects the descendingmovement of the finger F. As the finger F reaches the first detectionreference 40 a, the detection reference control unit 204 decides thatthe finger F has reached the first detection reference 40 a based on thedetection output provided from the operation detector 13 and once thisdecision is made, the display control unit 202 changes the display modefor the icon 30A. The display mode may be switched by raising thedisplay luminance, by flashing the display for a highlighted displayeffect, or by altering the display color. As the display mode for theicon 30A changes in this manner, the user is able to verify that theicon 30A has been selected with his finger.

As the user's finger F moves further downward and reaches the seconddetection reference 40 b, the detection reference control unit 204decides that the finger F has reached the second detection reference 40b based on the detection output provided by the operation detector 13,and the display control unit 202 switches the display content in themidair image 30 based on this decision. Namely, the second detectionreference 40 b has a function similar to that of the detection reference40 described in reference to the fifth embodiment. It is to be notedthat while the display control unit 202 switches the display content ofthe midair image 30 based on the decision that the finger F has reachedthe second detection reference 40 b in the example described above, thepresent invention is not limited to this example. For instance, once itis decided that the finger F has reached the second detection reference40 b, the display control unit 202 may execute control for displayingmovie as the midair image 30 and playing the movie based on thedecision. Once it is decided that the finger F has reached the seconddetection reference 40 b, the display control unit 202 may executescroll control for the midair image 30 based on the decision.

Next, the calibration processing executed in the sixth embodiment willbe explained by assuming that it is executed in the second calibrationprocessing mode. While the second calibration processing is underway, adescending movement of the user's finger F toward the icon 30A in themidair image 30 is likely to stop once the user feels that he hasselected the icon 30A, i.e., once he decides that the finger F hasreached the first detection reference 40 a, as shown in FIG. 43(a). Thedetection reference control unit 204 shown in FIG. 36 determines thefinger reach position 50 or the designated position 50A based on thepoint at which the descending movement of the user's finger F hasstopped, indicated in the detection output provided by the operationdetector 13. The reach position 50 or the designated position 50A islocated at a point further upward relative to the first detectionreference 40 a by a distance ΔH.

Since the reach position 50 or the designated position 50A is furtherupward relative to the first detection reference 40 a by the distanceΔH, the display position control unit 220 moves the display position ofthe midair image 30 downward by the distance ΔH, i.e., to a position 30indicated by the dotted line.

Through the downward movement of the midair image 30, the positionalrelationship between the midair image 30 and the first detectionreference 40 a is calibrated. Since the distance between the midairimage 30 and the second detection reference 40 b becomes smaller thanthe distance between the midair image 30 and the first detectionreference 40 a through this calibration processing, the detectionreference control unit 204 moves the second detection reference 40 bdownward to a position 40 b indicated by the dotted line in FIG. 43(b),so as to equalize the distance between the midair image 30 and thesecond detection reference 40 b with the distance between the midairimage 30 and the first detection reference 40 a. The downward movementof the midair image 30 reduces the distance between the position of themidair image 30 and the position of the second detection referenced 40b. For this reason, the ease of operation by the user may be compromisedsince the user will feel that his finger reaches the second detectionreference 40 b immediately after it touches the midair image 30.However, better ease of operation by the user is assured by changing thedistance between the midair image 30 and the second detection reference40 b to the suitable distance. When the distance between the midairimage 30 and the second detection reference 40 b is equalized with thedistance between the midair image 30 and the first detection reference40 a, the user is able to easily discern the distance between the midairimage 30 and the second detection reference 40 b based on the distancebetween the midair image 30 and the first detection reference 40 a.

When the reach position 50 or the designated position 50A is locatedfurther downward relative to the first detection reference 40 a by adistance −ΔH, as shown in FIG. 44(a), the display position control unit220 and the display position change unit 500 move the display positionof the midair image 30 upward by the distance ΔH, as indicated in FIG.44(b). As the midair image 30 is moved as described above, the detectionreference control unit 204 moves the second detection reference 40 b upto a position 40 b indicated by the dotted line in FIG. 44(c). As aresult, the distance between the midair image 30 and the seconddetection referenced 40 b is equalized with the distance between themidair image 30 and the first detection reference 40 a. When the midairimage 30 is moved upward, the distance between the position of themidair image 30 and the position of the second detection reference 40 blengthens. For this reason, the ease of operation by the user may becompromised, as the user is likely to feel that his finger, havingtouched the midair image 30, needs to move over quite a distance toreach the second detection reference 40 b. However, better ease ofoperation by the user is assured by changing the distance between themidair image 30 and the second detection reference 40 b to the suitabledistance. Since the distance between the midair image 30 and the seconddetection reference 40 b is equalized with the distance between themidair image 30 and the first detection reference 40 a, the user is ableto easily discern the distance between the midair image 30 and thesecond detection reference 40 b based on the distance between the midairimage 30 and the first detection reference 40 a.

While the calibration processing is executed in the second calibrationprocessing mode, as described above, it can be executed in a similarmanner in the first calibration processing mode as well.

Variation 1 of the Sixth Embodiment

The display device achieved in the sixth embodiment described abovechanges the positional relationship between the first detectionreference 40 a and the midair image 30 by moving the midair image 30 andthen moves the second detection reference 40 b so as to set the distancebetween the midair image 30 taking a new position through the move andthe second detection reference 40 b substantially equal to the distancebetween the midair image 30 and the first detection reference 40 a.Variation 1 of this embodiment will be described next. In variation 1,the positional relationship between the first detection reference 40 aand the midair image 30 is changed by moving the midair image 30, as inthe display device achieved in the sixth embodiment, but the positionalrelationship between the midair image 30 and the second detectionreference 40 b is changed by moving the second detection reference 40 bbased on the finger reach position or the designated position determinedrelative to the second detection reference.

The display device in variation 1 brings up on display the midair image30 as shown in FIG. 42, and sets the first and second detectionreferences 40 a and 40 b at the initial positions, as does the displaydevice in the sixth embodiment. The calibration processing executed inthis variation will be explained in reference to FIGS. 45(a), 45(b) and45(c). It is to be noted that FIG. 45(a) is identical to FIG. 39(a).

A descending movement of the user's finger F toward a first icon 30A inthe midair image 30 is likely to stop once the user feels that he hasselected the first icon 30A, i.e., once he decides that the finger F hasreached the first detection reference 40 a, as shown in FIG. 45(a). Thedetection reference control unit 204 determines the finger reachposition 50 or the designated position 50A based on the detection outputprovided by the operation detector 13. Since the reach position 50 orthe designated position 50A is located at a point further upwardrelative to the first detection reference 40 a by a distance ΔH, thedisplay position control unit 220 moves the display position of themidair image 30 to a position further downward by an extentsubstantially equal to the distance ΔH, i.e., to a position 30 indicatedby the dotted line. Through the downward movement of the midair image30, the positional relationship between the midair image 30 and thefirst detection reference 40 a is changed, i.e., the positionalrelationship is calibrated.

Following the calibration, the user moves his finger F further downward,and when he feels that an operation at the icon 30A has been performed,i.e., when he feels that his finger F has reached the second detectionreference 40 b, he is likely to stop the descending movement of thefinger F. As indicated in FIG. 45(b), the detection reference controlunit 204 determines the reach position 50 taken by the finger or thedesignated position 50A relative to the second detection reference 40 bbased on the detection output provided by the operation detector 13.Since the finger reach position 50 or the designated position 50A islocated further upward relative to the second detection reference 40 bby the distance ΔH, the detection reference control unit 204 in FIG. 36moves the second detection reference 40 b upward by, for instance, anextent substantially equal to the distance ΔH based on the finger reachposition 50 or the designated position 50A. Through this processing, thesecond detection referenced 40 b is moved upward to a position 40 aindicated by the dotted line in FIG. 45(c). As the second detectionreference 40 b moves upward as described above, the positionalrelationship between the midair image 30 and the second detectionreference 40 b is changed, i.e., the positional relationship iscalibrated.

It is to be noted that when the finger reach position 50 or thedesignated position 50A relative to the first detection reference 40 ais further downward relative to the first detection reference 40 a, thedisplay position control unit 220 moves the midair image 30 upward basedon the finger reach position 50 or the designated position 50A, as inthe display device achieved in the sixth embodiment described inreference to FIG. 44(a) and FIG. 44(b). As the midair image 30 movesupward, the positional relationship between the midair image 30 and thefirst detection reference 40 a is changed, i.e., the positionalrelationship is calibrated.

When the finger reach position 50 or the designated position 50A,determined in relation to the second detection reference 40 b, isfurther downward relative to the second detection reference 40 b, thedetection reference control unit 204 moves the second detectionreference 40 b downward, based on the reach position 50 or thedesignated position 50A. As the second detection reference 40 b movesdownward, the positional relationship between the midair image 30 andthe second detection reference 40 b is changed, i.e., the positionalrelationship is calibrated. As described above, the positionalrelationship between the midair image 30 and the first detectionreference 40 a is first changed by moving the midair image 30 and thenthe positional relationship between the midair image 30 and the seconddetection reference 40 b is changed by moving the second detectionreference 40 b, so as to change both the positional relationship betweenthe midair image 30 and the first detection reference 40 a and thepositional relationship between the midair image 30 and the seconddetection reference 40 b to suitable positional relationships.

It is to be noted that as an alternative to the control executed invariation 1 as described above, the positional relationship between themidair image 30 and the first detection reference 40 a may be changed bymoving the midair image 30 based on the finger reach position 50 or thedesignated position 50A determined relative to the first detectionreference 40 a and the positional relationship between the midair image30 and the second detection reference 40 b may then be changed byfurther moving the midair image 30 based on the finger reach position 50or the designated position 50A determined relative to the seconddetection reference 40 b. In this case, the positional relationshipbetween the midair image 30 and the first detection reference 40 a andthe positional relationship between the midair image 30 and the seconddetection reference 40 b can be changed by moving the midair image 30alone, through simple control.

Variation 2 of the Sixth Embodiment

Variation 2 of the display device achieved in the sixth embodiment willbe described next. It is distinguishable from the sixth embodiment andvariation 1 thereof described above in the method with which the midairimage 30 is made to move. Namely, the display position of the midairimage 30 is moved in correspondence to a descending movement of theuser's finger.

After the user's finger, moving down toward an icon 30A, reaches thefirst detection reference 40 a and the display mode for the icon 30A isswitched in response in the midair image operation mode in the displaydevice in variation 2, the finger keeps moving downward. As it reachesthe display position of the midair image 30, the display positioncontrol unit 220 decides that the finger has reached the displayposition of the midair image 30 based on the detection output providedby the operation detector 13 and moves the display position of themidair image 30 in accordance with the descending movement of thefinger. The display position control unit 220 controls the displayposition of the midair image 30 so that the midair image displayposition and the position of the descending finger are both held withina predetermined range. Under such control, the display position of themidair image 30 can be made to move downward to trail the descendingfinger. By setting the display position of the midair image 30 so as toalways take a position further downward relative to the descendingfinger and controlling the display position of the midair image 30 viathe display position control unit 220 so that the display position ofthe midair image 30 moves downward in accordance with the descendingfinger, it is possible that the user's finger does not move through themidair image 30.

As the descending finger and the descending midair image 30, moving totrail the descending movement of the finger, both reach the seconddetection reference 40 b, the detection reference control unit 204decides that the finger has reached the second detection reference 40 band the display control unit 202 brings up on display a reproducedimage.

As described above, once the finger reaches the midair image 30, themidair image 30 moves to trail the descending movement of the finger,which creates a user perception of the descending finger being guided bythe midair image 30 to the second detection reference 40 b to enable thefinger to reach the second detection reference 40 b with a high degreeof reliability.

It is to be noted that while the display device 1 in the sixthembodiment and variations 1 and 2 thereof includes at least the controlunit 20, the display unit 11 and the operation detector 13, the presentinvention may instead be adopted in a control device configured with thecontrol unit 20 alone or a control device configured with the controlunit 20 and the operation detector 13. The control unit 20 may includeat least the calibration unit 203, the display position control unit 220and the detection reference control unit 204. A structural element maybe added as needed in order to realize the various advantages describedin reference to the sixth embodiment or variations 1 or 2 thereof.

Seventh Embodiment

The display device achieved in the seventh embodiment will be describedbelow. The display device in this embodiment is structurally similar tothe display device 100 achieved in the fourth embodiment described inreference to FIG. 29, FIG. 31 and FIG. 32, and the display device 100achieved in variation 1 of the fourth embodiment, described in referenceto FIG. 33 and FIG. 34. As with the display devices 1 achieved in thefifth embodiment and variations 1 through 4 thereof, the sixthembodiment and variation 1 thereof, the display device 100 in theseventh embodiment is configured so as to enable change of the midairimage display position.

As shown in FIG. 46, the display device 100 in the embodiment includes adisplay position change unit 500 and a display position control unit 220in addition to the structural elements of the display device 100achieved in the fourth embodiment, as shown in FIG. 29. As with thefifth embodiment, variations 1 through 4 thereof, the sixth embodimentand variation 1 thereof, the detection reference control unit 204determines the finger reach position 50 based on the detection outputprovided by the operation detector 13. Based upon the finger reachposition 50, the display position control unit 206 causes the displayposition change unit 500 to move the position of the midair image 300along the optical axis of the image forming optical system 12 based onthe finger reach position 50. At this time, the display position changeunit 500 moves the midair image 30 along the Z direction by moving thedisplay unit 111 along the X direction. Namely, it is able to move themidair image 30 toward the + side along the Z direction by moving thedisplay unit 111 toward the + side along the X direction and move themidair image 30 toward the − side along the Z direction by moving thedisplay unit 111 toward the − side along the X direction. It will beobvious, however, that the display position change unit 500 may move theimage forming optical system 112 in parallel without moving the displayunit 111 or it may move both the image forming optical system 112 andthe display unit 111.

In the various embodiments and variations thereof described above,calibration processing is executed so as to change the positionalrelationship between the detection reference 40 and the midair image 30(or an icon 30A or the like) by moving the position of the detectionreference 40 or by moving the display position of the midair image 30.However, the positional relationship between the detection reference 40and the midair image 30 may be change by moving both the detectionreference 40 and the midair image 30.

It is to be noted that while the display device 100 in the seventhembodiment includes at least the control unit 20, the display unit 11and the operation detector 113, the present invention may instead beadopted in a control device configured with the control unit 20 alone ora control device configured with the control unit 20 and the displayunit 111. The control unit 20 may include at least the calibration unit203 and the display position control unit 220. A structural element maybe added as needed in order to realize the various advantages describedin reference to the seventh embodiment.

Eighth Embodiment

In the embodiments and variations thereof described above, thepositional relationship between the detection reference and the midairimage is changed by controlling or changing the detection referenceand/or the midair image based on the fingertip reach position or thedesignated position through the calibration processing. The eighthembodiment, in which the detection reference is changed when apredetermined non-contact operation, performed while the calibrationprocessing is underway, is not detected by the detection reference, willbe described next.

The display device 1 achieved in this embodiment adopts a structuresimilar to the display device 1 achieved in the first embodiment,described in reference to FIG. 1 and FIG. 2. In the midair imageoperation mode, the display control unit 202, the display unit 11 andthe image forming optical system 12 at the display device 1 achieved inthe eighth embodiment display a midair image 30 for the midair imageoperation mode, as shown in FIG. 47(a) and FIG. 47(b). The midair image30 in FIG. 47(a) includes two rectangular icons 30D and 30E.

The detection reference control unit 204 sets rectangular parallelepipeddetection references 42 at initial positions, each in correspondence toone of the two icons 30D and 30E included in the midair image 30, asshown in FIG. 47(b) and FIG. 47(c). The areal size of a lateral sectionof the detection reference 42 corresponding to the icon 30D correspondsto the size of the icon 30D, as clearly indicated in FIG. 47. D1indicates the depth measured along the up/down direction, i.e., alongthe Z direction. Namely, the length W1 of a side of the lateral sectionof the rectangular parallelepiped detection reference 42 is equal to thelength W1 of a side of the icon 30D and the length W2 of another side ofthe lateral section is equal to the length W2 of another side of theicon 30D.

An upper plane, a lower plane, a side plane defined with the length W2and the depth D1, and another side plane defined with the length W1 andthe depth D1 of the rectangular parallelepiped detection reference 42will be respectively referred to as an upper reference plane 42 a, alower reference plane 42 b, a side reference plane 42 c and a sidereference plane 42 d.

While the embodiment will be described by assuming that the detectionreferences 42 are rectangular parallelepiped references, the presentinvention is not limited to this example and may be adopted inconjunction with spherical detection references, cylinder-shapeddetection references, prismatic detection references or detectionreferences assuming a shape other than these.

The midair image 30 is set so that it takes a position at the halfwaypoint between the upper reference plane 42 a and the lower referenceplane 42 b, i.e., so that the distance between the midair image 30 andthe upper reference plane 42 a is equal to the distance between themidair image 30 and the lower reference plane 42 b. It is to be notedthat the midair image 30 does not need to take a position at preciselythe halfway point between the upper reference plane 42 a and the lowerreference plane 42 b, and the midair image 30 may instead be set at aposition at which the distance between the midair image 30 and the upperreference plane 42 a and the distance between the midair image 30 andthe lower reference plane 42 b are not equal to each other, at aposition further upward relative to the upper reference plane 42 a or ata position further downward relative to the lower reference plane 42 b,as long as the midair image 30 (the icons 30D and 30E) and the referenceplanes 42 a and 42 b of the detection reference 42 are verticallyaligned when viewed along the Z direction.

It is to be noted that the detection reference 42 corresponding to theicon 30E also assumes a rectangular parallelepiped shape having apredetermined depth with a lateral section thereof having a shapecorresponding to the shape of the icon 30E, as does the detectionreference 42 corresponding to the icon 30D.

In the midair image operation mode, by a predetermined non-contactoperation toward the detection reference 42 by the user, the displaydevice 1 executes a function allocated to the icon 30D or the icon 30E.FIGS. 48(a) through 48(c) present examples of predetermined non-contactoperations 600A through 600C (may be collectively referred to as apredetermined non-contact operation 600) that may be performed in theembodiment. FIG. 48 schematically illustrates the predeterminednon-contact operations 600A through 600C by using arrows, eachindicating a path of the movement of the finger F. The user performingthe predetermined non-contact operation 600A shown in FIG. 48(a) moveshis finger F downward by a distance L1, makes a U-turn with the finger Fand then moves the finger F upward by the distance L1. Namely, thepredetermined non-contact operation 600A leaves a U-turn path with thedownward movement and the upward movement made over distances equal toeach other. Instead of making a U-turn, i.e., instead of leaving aU-shaped path, a V-shaped path may be left through the predeterminednon-contact operation 600A. As a further alternative, the finger Fperforming the predetermined non-contact operation 600A may movedownward by the distance L1 and then move upward by the distance L1along the same path. The distance L1, over which the downward movementis made and the distance L1, over which the upward movement is made inthe predetermined non-contact operation 600A, may be different from eachother. The predetermined non-contact operation 600A performed in theembodiment simply needs to include a downward movement of the finger,immediately followed by an upward movement of the finger.

The user performing the predetermined non-contact operation 600B shownin FIG. 48(b) first moves his finger F downward by the distance L1 andthen holds the finger F still for a predetermined length of time. Theuser performing the non-contact operation 600C shown in FIG. 48(c) firstmoves his finger F downward by the distance L1 and then moves the fingerF sideways at least by a predetermined distance L2.

Instead of performing the predetermined non-contact operation 600indicated by the path of one of the various paths of movement of thefinger F described above, the user may perform a non-contact operationthat will leave another path of movement, as long as the path of themovement (the path of movement of the finger F or a hand) can bedetected by the operation detector 13.

In the midair image operation mode, once a predetermined non-contactoperation 600 is detected by a detection reference by the operationdetector 13, the detection reference control unit 204 decides that thefinger F has performed an operation at the icon display position basedon the detection output provided by the operation detector 13 upondetecting the movement of the user's finger F.

In the example presented in FIG. 49, the detection reference controlunit 204 decides that the non-contact operation 600A, among thepredetermined non-contact operations 600 described earlier, has beenperformed at the detection reference 42. Through a predeterminednon-contact operation 600A1, the finger F moves downward by the distanceL1 from the upper reference plane 42 a, makes a U-turn and moves upwardby the distance L1 until the finger F reaches the upper reference plane42 a. Through a predetermined non-contact operation 600A2, the finger Fmoves downward by the distance L1, then makes a U-turn and moves upwardby the distance L1 in the space between the upper reference plane 42 aand the lower reference plane 42 b. Through a predetermined non-contactoperation 600A3, the finger F moves downward by the distance L1, makes aU-turn at the lower reference plane 42 b and moves upward by thedistance L1.

As described earlier, the detection reference control unit 204 decidesthat the predetermined non-contact operation 600A has been performed atthe detection reference 42 if the downward movement of the finger overthe distance L1, the U-turn, the upward movement over the distance L1are all made at the detection reference 42 through the predeterminednon-contact operation 600A, as shown in FIG. 49. Namely, the detectionreference control unit 204 detects the predetermined non-contactoperation 600A by the detection reference 42.

While the method adopted when the detection reference control unit 204determines whether or not a predetermined non-contact operation 600 hasbeen performed at the detection reference 42 in reference to thepredetermined non-contact operation 600A used as an example, such adecision may be made in a similar manner with regard to otherpredetermined non-contact operations such as the predeterminednon-contact operations 600B and 600C. The detection reference controlunit 204 decides that a predetermined non-contact operation 600 has beenperformed at the detection reference 42 if the predetermined non-contactoperation 600 has been performed in its entirety at the detectionreference 42. Even if part of the predetermined non-contact operation600 has been performed outside a detection reference 41, it does notdecide that the predetermined non-contact operation 600 has beenperformed at the detection reference 42. When the predeterminednon-contact operation 600 is performed with the finger moving by thedistance L1 along the up/down direction, the detection reference 42needs to achieve a depth D1, i.e., the distance between the upperreference plane 42 a and the lower reference plane 42 b (the lengthalong the Z direction) at least equal to or greater than, the distanceL1, and accordingly, the depth D1 may be set to, for instance, 1.5 to 3times the distance L1.

It is to be noted that outside the detection reference 41 in FIG. 49 isspace outside the detection reference 42. In more specific terms, it isthe space outside the space defined by the upper reference plane 42 a,the lower reference plane 42 b, the side reference plane 42 c and theside reference plane 42 d of the detection reference 42 shown in FIG.47(c).

A predetermined non-contact operation 600 may be detected outside thedetection reference 41, as will be described next. A predeterminednon-contact operation is detected outside the detection reference 41 ifthe predetermined non-contact operation 600 in its entirety is detectedoutside the detection reference 41.

While the embodiment and variations thereof will be explained inreference to the predetermined non-contact operation 600A chosen as anexample, a technology equivalent to that described below may be adoptedin conjunction with other non-contact operations such as the non-contactoperations 600B and 600C.

FIG. 50 presents examples of the predetermined non-contact operation600A in its entirety detected outside the detection reference 41. InFIG. 50(a), the entire predetermined non-contact operation 600A isperformed with the finger F at a position above the upper referenceplane 42 a of the detection reference 42. In this situation, thepredetermined non-contact operation 600A in its entirety is detectedoutside the detection reference 41 via the operation detector 13 and thedetection reference control unit 204.

FIG. 50(b) shows a predetermined non-contact operation 600Aa in itsentirety performed with the finger F at a position below the lowerreference plane 42 b of the detection reference 42 and a predeterminednon-contact operation 600Ab in its entirety performed with the finger Fat a position outside the side reference plane 42 c of the detectionreference 42. Under these circumstances, the entire predeterminednon-contact operation 600Aa and the entire predetermined non-contactoperation 600Ab are both detected outside the detection reference 41 bythe operation detector 13 and the detection reference control unit 204.The method through which the operation detector 13 and the detectionreference control unit 204 detect a predetermined non-contact operation600 outside the detection reference 41 will be explained next. Theoperation detector 13 sequentially detects the movement of the finger F.Next, based on the detection output provided by the operation detector13, the detection reference control unit 204 determines whether or notthe path of the movement of the finger F corresponds to a predeterminednon-contact operation 600 and a decision with regard to the positionstaken by the finger F along the path of its movement (in the detectionreference 42, outside the detection reference 41 or both at thedetection reference 42 and outside the detection reference 41). Based onthe results obtained through the decision-making, the predeterminednon-contact operation 600 can be detected outside the detectionreference 41.

Next, in reference to FIG. 51, FIG. 52 and FIG. 53, the calibrationprocessing executed when the predetermined non-contact operation 600 isdetected outside the detection reference 41 will be described. FIG. 51illustrates the predetermined non-contact operation 600A detectedoutside the detection reference 41 at a position further upward relativeto the upper reference plane 42 a of the detection reference 42. It isto be noted that while the calibration processing described below isexecuted by using the midair image 30 for midair image operation, it mayinstead be executed by using a midair image 300 for calibrationprocessing, such as that shown in FIG. 4.

Once the user's finger, moving downward in order to perform an operationat the display position of the icon 30D in the midair image 30, reachesthe upper limit 13 a of the detection range 13A of the operationdetector 13, as shown in FIG. 51(a), the operation detector 13sequentially detects the descending movement of the finger and detectionoutputs, provided as the finger moves, are sequentially stored into thestorage unit 205. Based on the detection outputs provided by theoperation detector 13 and stored in the storage unit 205, the detectionreference control unit 204 determines whether or not the path of themovement of the finger F corresponds to the predetermined non-contactoperation 600A and also determines whether or not the path of themovement of the finger F in its entirety is at the detection reference42.

Upon deciding that the predetermined non-contact operation 600A has beenperformed and that the predetermined non-contact operation has beenperformed in its entirety outside the detection reference 41, thedetection reference control unit 204 calculates, based on the detectionoutputs provided by the operation detector 13 and stored in the storageunit 205, a distance ΔH10 between the start position at which thepredetermined non-contact operation 600A has started and the upperreference plane 42 a. While the distance ΔH10 may be calculated based onthe operation start position for the predetermined non-contact operation600A and the position of the upper reference plane 42 a as describedabove, it may instead be calculated through the following alternativemethod. Namely, the distance ΔH10 can also be calculated by determiningthe lowest position assumed during the predetermined non-contactoperation 600A, i.e., the reach position of the predeterminednon-contact operation 600A, based on the detection outputs provided bythe operation detector 13 and stored in the storage unit 205,calculating the distance between the reach position of the predeterminednon-contact operation 600A and the position assumed at the upperreference plane 42 a and adding the distance L1, over which thepredetermined non-contact operation 600A spans to the distance thuscalculated.

Once the distance ΔH10 is calculated, the detection reference controlunit 204 moves the entire detection reference 42 upward based on thedistance ΔH10, as shown in FIG. 51(b). The detection reference 42 havingbeen moved is indicated by the one-point chain lines. The extent towhich the detection reference 42 is moved upward may be substantiallyequal to the distance ΔH10, as indicated in FIG. 51(b), or it may begreater or smaller than the distance ΔH10. As described above, when thepredetermined non-contact operation performed by the user is detectedoutside the detection reference 41 at a position further upward relativeto the detection reference 42, the detection reference 42 is changed bymoving the entire detection reference 42 up toward the position at whichthe predetermined non-contact operation has been performed. As a result,when the operation by the user fails to reach the detection reference 42and is thus not effective, the detection reference 42 is changed incorrespondence to position of the operation by the user, making itpossible to lessen the sense of operational discomfort that may beotherwise experienced by the user.

FIG. 52 illustrates the predetermined non-contact operation 600Adetected outside the detection reference 41 at a position furtherdownward relative to the lower reference plane 42 b of the detectionreference 42. Upon deciding, based on the detection outputs provided bythe operation detector 13 and stored in the storage unit 205, that thepredetermined non-contact operation 600A has been performed and that thepredetermined non-contact operation has been performed outside thedetection reference, as shown in FIG. 52(a), the detection referencecontrol unit 204 calculates a distance ΔH10 between the lowest positiontaken in the movement path corresponding to the predeterminednon-contact operation 600A, i.e., the reach position taken during thepredetermined non-contact operation 600A, and the lower reference plane42 b of the detection reference 42. Once the distance ΔH10 iscalculated, the detection reference control unit 204 moves the entiredetection reference 42 downward based on the distance ΔH10, as shown inFIG. 52(b). The detection reference 42 having been moved is indicated bythe one-point chain lines. The extent to which the detection reference42 is moved downward may be substantially equal to the distance ΔH10, asindicated in FIG. 52(b), or it may be greater or smaller than thedistance ΔH10. As described above, when the predetermined non-contactoperation performed by the user is detected outside the detectionreference 41 at a position further downward relative to the detectionreference 42, the detection reference 42 is changed by moving the entiredetection reference 42 down toward the position at which thepredetermined non-contact operation has been performed. As a result,when the operation by the user passes through the detection reference 42and is thus not effective, the detection reference 42 is changed incorrespondence to the position of the operation by the user, making itpossible to lessen the sense of operational discomfort that may beotherwise experienced by the user.

FIG. 53 illustrates the predetermined non-contact operation 600Adetected outside the detection reference 41 at a position outside theside reference plane 42 c of the detection reference 42. Upon deciding,based on the detection outputs provided by the operation detector 13 andstored in the storage unit 205, that the predetermined non-contactoperation 600A has been performed and that the predetermined non-contactoperation has been performed outside the side reference plane 42 c, asshown in FIG. 53(a), the detection reference control unit 204 calculatesa distance ΔH10 between the side reference plane 42 c of the detectionreference 42 and the part of the movement path of the predeterminednon-contact operation 600A that is furthest away from the side referenceplane 42 c. Once the distance ΔH10 is calculated, the detectionreference control unit 204 moves the entire detection reference 42sideways toward the position at which the predetermined non-contactoperation 600A has been performed based on the distance ΔH10, as shownin FIG. 53(b). The detection reference 42 having been moved is indicatedby the one-point chain lines. The extent to which the detectionreference 42 is moved sideways may be substantially equal to thedistance ΔH10, as indicated in FIG. 53(b), or it may be greater orsmaller than the distance ΔH10. As described above, when thepredetermined non-contact operation performed by the user is detectedoutside the detection reference 41 at a position outside the sidereference plane 42 c or 42 d of the detection reference 42, thedetection reference 42 is changed by moving the entire detectionreference 42 toward the position at which the predetermined non-contactoperation has been performed. As a result, when the operation by theuser is performed outside the detection reference 42 and is thus noteffective, the detection reference 42 is changed in correspondence tothe position of operation by the user, making it possible to lessen thesense of operational discomfort that may be otherwise experienced by theuser.

It is to be noted that while the detection reference 42 is changed bythe change quantity ΔH10 calculated as described above in the examplespresented in FIGS. 51 through 53, the detection reference 42 may insteadbe changed by change quantity calculated by adding a predeterminedquantity h to the distance ΔH10. The predetermined quantity h may be,for instance, a value obtained by averaging differences manifesting withregard to the reach position of the predetermined non-contact operation600 (each representing the difference between the reach position of thenon-contact operation and the closest reference plane of the detectionreference 42 in a specific instance) or a value obtained by averagingdifferences with regard to the start positions of a plurality ofnon-contact operations 600 (each representing the difference between thenon-contact operation start position and the closest reference plane ofthe detection reference 42 in a specific instance). The predeterminedquantity h may take a preselected fixed value. In such a case, thedetection reference 42 moves by an extent representing the sum of thedistance ΔH10 and the predetermined quantity h used as a margin. Thismeans that, even when the non-contact operation cannot be performedexactly at the same position at which the non-contact operation has beenperformed during the calibration processing, the non-contact operationby the user can still be detected at the detection reference 42, as longas the operation position error stays within the range defined by thepredetermined quantity h. In other words, even when the start positionor the reach position of the non-contact operation performed by the userchanges from session to session, the user non-contact operation canalways be detected by the detection reference 42. As a result, bychanging the detection reference by an extent indicated by the sum ofthe distance ΔH10 and the predetermined quantity h, the rate ofnon-contact operation detection by the detection reference 42 can beraised compared to the detection rate achieved by changing the detectionreference 42 by an extent matching the distance ΔH10.

An operation different from the predetermined non-contact operation 600may be detected outside the detection reference 41, as will be explainednext. An operation different from than the predetermined non-contactoperation 600 detected outside the detection reference 41 is part of thepredetermined non-contact operation 600, instead of the entirepredetermined non-contact operation 600, detected outside the detectionreference 41.

FIG. 54 presents examples of part of the predetermined non-contactoperation 600A detected outside the detection reference 41. FIG. 54(a)shows that part of the predetermined non-contact operation 600Aperformed with the finger F, i.e., the part corresponding to thedistance ΔH10, is performed at a position further upward relative to theupper reference plane 42 a of the detection reference 42 with theremainder of the non-contact operation performed at the detectionreference 42. In other words, the predetermined non-contact operation600A is made up with the part of the predetermined non-contact operation600A, which is detected by the detection reference 42, and the part ofthe predetermined non-contact operation 600A, which is detected outsidethe detection reference 41.

Under such circumstances, part of the predetermined non-contactoperation 600A is detected outside the detection reference 41 by theoperation detector 13 and the detection reference control unit 204.

FIG. 54(b) shows that part of a predetermined non-contact operation600Aa performed with the finger F, i.e., the part corresponding to thedistance ΔH10 is performed at a position further downward relative tothe lower reference plane 42 b of the detection reference 42 with theremainder of the non-contact operation performed at the detectionreference 42. In other words, the predetermined non-contact operation600Aa is made up with the part of the predetermined non-contactoperation 600Aa, which is detected by the detection reference 42, andthe part of the predetermined non-contact operation 600Aa, which isdetected outside the detection reference 41.

Part of a predetermined non-contact operation 600Ab performed with thefinger F, i.e., the part corresponding to the distance ΔH10 is performedat a position further outside the side reference plane 42 c and theremainder of the operation is performed at the detection reference 42.In other words, the predetermined non-contact operation 600Ab is made upwith the part of the predetermined non-contact operation 600Ab, which isdetected by the detection reference 42, and the part of thepredetermined non-contact operation 600Ab, which is detected outside thedetection reference 41.

In these situations, too, part of the predetermined non-contactoperation 600Aa or 600Ab is detected outside the detection reference 41by the operation detector 13 and the detection reference control unit204.

Next, in reference to FIG. 54, the calibration processing executed whenan operation different from the predetermined non-contact operation 600is detected outside the detection reference 41 will be explained.

The calibration processing executed when part of the predeterminednon-contact operation 600A is performed at the detection reference 42and the remaining operation is performed at a position further upwardrelative to the upper reference plane 42 a, as shown in FIG. 54(a), issimilar to that described in reference to FIG. 51. Namely, the entiredetection reference 42 is moved upward in the figure based on thedistance ΔH10.

The calibration processing executed when part of the predeterminednon-contact operation 600Aa is performed at the detection reference 42and the remaining operation is performed at a position further downwardrelative to the lower reference plane 42 b, as shown in FIG. 54(b), issimilar to that described in reference to FIG. 52. Namely, the entiredetection reference 42 is moved downward in the figure based on thedistance ΔH10.

The calibration processing executed when part of the predeterminednon-contact operation 600Ab is performed at the detection reference 42and the remaining operation is performed at a position further outsiderelative to the side reference plane 42 c, as shown in FIG. 54(b), issimilar to that described in reference to FIG. 53. Namely, the entiredetection reference 42 is moved sideways in the figure based on thedistance ΔH10.

An example in which the calibration processing described above isexecuted in the first calibration processing mode will be explained inreference to the flowchart presented in FIG. 55. It is to be noted thatthe flowchart in FIG. 55 shows the processing executed in steps S701through S709 and does not show the processing executed in subsequentsteps following step S709. The processing executed in step S709 andsubsequent steps is similar to the processing executed in step S9 andsubsequent steps in the flowchart presented in FIG. 6 and a repeatedexplanation is not provided. The processing executed in steps S701through S703 is similar to the processing executed in steps S1 throughS3 in the flowchart presented in FIG. 6. In step S704, a decision ismade based on detection outputs provided by the operation detector 13,as to whether or not the operation by the user (specifically, theoperation by the user toward the display position of the icon 300A, inthe midair image 300) is a predetermined non-contact operation. When itis a predetermined non-contact operation, an affirmative decision ismade in step S704 and the operation proceeds to step S705, whereas whenit is not a predetermined non-contact operation, a negative decision ismade in step S704 and the operation waits in standby until anaffirmative decision is made.

In step S705, a decision is made as to whether or not the predeterminednon-contact operation has been performed at the detection referenced 42.When the predetermined non-contact operation has been performed at thedetection reference 42, as shown in FIG. 49, an affirmative decision ismade in step S705, and the operation proceeds to step S708, which willbe explained later. When the predetermined non-contact operation has notbeen detected by the detection reference 42, i.e., (1) if the entirepredetermined non-contact operation has been detected outside thedetection reference 41 or (2) if part of the predetermined non-contactoperation has been detected by the detection reference 42 and theremaining part has been detected outside the detection reference 41, anegative decision is made in step S705 and the operation proceeds tostep S706. In step S706, the change quantity for the detection reference42 is calculated based on the positional relationship between thepredetermined non-contact operation and the detection reference 42, andthen the operation proceeds to step S707.

In step S707, the position of the detection reference 42 is changedbased on the change quantity calculated in step S706 before theoperation proceeds to step S708. In step S708, the first calibrationprocessing mode ends and the operation proceeds to step S709. In stepS709, the midair image operation mode starts. As described above, if thepredetermined non-contact operation performed by the user is notdetected by the detection reference, the position of the detectionreference is changed. In other words, the central position assumed inthe detection reference 42 along the up/down direction and/or thecentral position assumed in the detection reference 42 along theleft/right direction is changed. With the detection reference positionchanged as described above, the user is able to perform an operation atthe position suited to the particular user. The positional relationshipbetween the detection reference and the midair image can be changed tothat suited to the operation by the user.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, the calibrationprocessing may be executed as shown in the flowchart presented in FIG.55 in the second calibration processing mode as well.

It is to be noted that while a detection reference 42 is set incorrespondence to each of the icons 30D and 30E in the eighth embodimentdescribed above, the present invention is not limited to this exampleand a common detection reference 42 may be set for a plurality of iconsor a single detection reference 42 may be set over the entire range ofthe midair image 30.

Variation 1 of the Eighth Embodiment

In the eighth embodiment described above, the detection reference 42 ischanged along the up/down direction and/or the left/right directionbased on the positional relationship between the position in space atwhich the predetermined non-contact operation 600 is detected and thedetection reference 42. In other words, the central position of thedetection reference 42 assumed along the up/down direction and/or thecentral position assumed along the left/right direction is changed. Thepositional relationship achieved in space by the detection reference 42and the predetermined non-contact operation 600 may be changed bychanging the depth D1 of the detection reference 42, as in the displaydevice 1 achieved in variation 1. For instance, when the predeterminednon-contact operation 600A is detected outside the detection reference41 further upward relative to the detection reference 42, as shown inFIG. 50(a), the upper reference plane 42 a alone may be changed upwardby the change quantity ΔH10 without altering the position of the lowerreference plane 42 b. Namely, the central position of the detectionreference 42 assumed along the up/down direction may be changed byaltering the depth D1 of the detection reference 42. As an alternative,the upper reference plane 42 a may be changed upward by the changequantity ΔH10 and the lower reference plane 42 b may be changed downwardby the change quantity ΔH10. Namely, the detection reference 42 may bechanged by altering the depth D1 of the detection reference 42 by equalchange quantities ΔH10 on the upper side and the lower side thereofwithout having to alter the central position of the detection reference42 assumed along the up/down direction. It is to be noted that when thepredetermined non-contact operation 600Aa is detected further downwardrelative to the detection reference 42, as shown in FIG. 50(b), theposition of the lower reference plane 42 b may be changed downward bythe change quantity ΔH10, or the position of the lower reference plane42 b and the position of the upper reference plane 42 a may berespectively changed downward and upward by the change quantity ΔH10. Itis to be noted that when the predetermined non-contact operation 600Abis detected further to the right relative to the detection reference 42,the position of the side reference plane 42 c can be changed along theleft/right direction in a similar manner. Namely, the detectionreference 42 may be changed by altering the central position of thedetection reference 42 along the left/right direction or by altering thewidth of the detection reference 42 without changing the centralposition.

Variation 2 of the Eighth Embodiment

The display device 1 achieved in variation 2 will be described next.When the predetermined non-contact operation 600 performed during thecalibration processing is detected outside the detection reference 41,the display device 1 in variation 2 changes the detection reference 42provided that the distance between the predetermined non-contactoperation 600 and the detection reference 42 is equal to or less than apredetermined value. The predetermined non-contact operation 600A may bedetected outside the detection reference 41 at a position further upwardrelative to the detection reference 42, as shown in FIG. 50(a). Undersuch circumstances, the display device 1 changes the detection reference42 by judging that the user has intended to perform an operation at thedisplay position of the midair image if it is decided that the distanceΔH10 is equal to or less than the predetermined value, i.e., if it isdecided that the predetermined non-contact operation 600A has beenperformed in the vicinity of the detection reference 42. When, on theother hand, it is decided that the distance ΔH10 is greater than thepredetermined value, i.e., if it is decided that the predeterminednon-contact operation 600A has been performed at a position away fromthe detection reference 42, the display device 1 judges that the userhas had no intention of performing an operation at the display positionof the midair image, that an erroneous operation has been performed orthat the user aborted an operation partway through, and accordingly doesnot change the detection reference 42.

If part of the predetermined non-contact operation 600A is detectedoutside the detection reference 41, as shown in FIG. 54, the position ofthe detection reference 42 may be changed based on the distance betweenthe position in space taken by the part of the predetermined non-contactoperation 600 detected outside the detection reference 41 and thedetection reference 42. For instance, a decision may be made as towhether or not the part of the non-contact operation 600 detectedfurther upward relative to the upper reference plane 42 a of thedetection reference 42, i.e., the distance ΔH10, as shown in FIG. 54(a),is equal to or less than a predetermined threshold value. When thedistance ΔH10 is equal to or less than the predetermined thresholdvalue, most of, but not all of, the predetermined non-contact operation600A, has been performed with the finger F at the detection reference42, as illustrated in FIG. 56(a). Under such circumstances, the displaydevice 1 judges that the user has had the intention of performing anoperation at the display position of the midair image and changes theposition of the detection reference 42. When the distance ΔH10 exceedsthe predetermined threshold value, most of the predetermined non-contactoperation 600A has been performed outside the detection reference 41, asillustrated in FIG. 56(b). In this case, the display device 1 judgesthat the user has had no intention of performing an operation at thedisplay position of the midair image, that an erroneous operation hasbeen performed or that the user has aborted an operation partwaythrough, and thus does not altar the position of the detection reference42.

Variation 3 of the Eighth Embodiment

In variation 3 of the eighth embodiment, the velocity or theacceleration of the user's fingertip is calculated based on thedetection output provided by the operation detector 13 and the positionof the detection reference 42 is modified based on the calculatedvelocity or acceleration, as in variation 1 of the first embodiment.Namely, the detection reference 42 is changed based on the velocity ofat least part of the predetermined non-contact operation 600 and,specifically, if the velocity of part of the predetermined non-contactoperation 600 is lower than a predetermined value. FIG. 57 is a blockdiagram showing a control unit 20, and a display unit 11 and anoperation detector 13 controlled by the detection unit 20 in the displaydevice 1 achieved in variation 3.

The expression “the velocity of at least part of the predeterminednon-contact operation 600” means that the velocity of an operationconstituting at least part of the predetermined non-contact operation600. An “operation constituting at least part of the predeterminednon-contact operation 600” may be, for instance, an operational segmentthrough which the user's finger moves from outside the detectionreference 41 toward the detection reference 42 during the predeterminednon-contact operation 600, in which the user's finger first moves from aposition outside the detection reference 41 toward the detectionreference 42 and then the finger immediately turns back toward theinitial position (the predetermined non-contact operation 600A). Or itmay be an operational segment through which the user's finger movestoward one end of the detection reference 42 during the predeterminednon-contact operation 600, in which the user's finger first moves from aposition at the detection reference 42 toward the one end of thedetection reference 42 and then immediately turns back (thepredetermined non-contact operation 600A).

It is to be noted that the detection reference 42 may be changed for asubsequent operation detection by monitoring the velocity (acceleration)through the entire predetermined non-contact operation 600 (e.g., fromthe start of the descending movement through the end of the subsequentascending movement in the predetermined non-contact operation 600A),calculating a velocity (acceleration) average value and deciding whetherthe operation is decisive or indecisive, based on the average value. Forinstance, when the operational velocity is high on average, there is thelikelihood that the user's finger will move through the detectionreference 42, and accordingly control may be executed so as to increasethe depth of the detection reference 42 for subsequent sessions.

The velocity/acceleration detection unit 206 in FIG. 57 reads out theelectrostatic capacitance value detected by the operation detector 13after each predetermined time interval and calculates the velocity ofthe finger movement based on a change having occurred in theelectrostatic capacitance value over the predetermined time interval, asin variation 1 of the first embodiment. Based on the velocity thuscalculated, it calculates the acceleration of the finger movement anddetermines whether or not the acceleration exceeds a predeterminedvalue. When the movement velocity and/or the movement accelerationcalculated by the velocity/acceleration detection unit 206 is indicatedby a value equal to or lower than a predetermined value, an operationpredicting unit 211 calculates, i.e., predicts, a path of the movementof the finger F, based on the finger movement velocity or accelerationoutput from the velocity/acceleration detector 206. Based on the path ofthe movement of the finger F predicted by the operation predicting unit211, the detection reference control unit 204 changes the detectionreference 42. Namely, if the predicted path of movement of the finger Fis not at the detection reference 42, it is decided that thepredetermined non-contact operation 600 is not detected at the detectionreference 42. In such a case, the detection reference 42 is changedbased on the change quantity ΔH10 having been calculated, as in theeighth embodiment. When, on the other hand, the predicted path ofmovement of the finger F is at the detection reference 42, it is judgedthat the predetermined non-contact operation 600 is detected by thedetection reference 42 and no change is made with regard to thedetection reference 42.

The operation predicting unit 211 may instead predict a path of movementof the finger F when the movement velocity and/or the movementacceleration calculated by the velocity/acceleration detection unit 206is indicated by a value equal to or greater than a predetermined valueand the detection reference 42 may be changed based on the predictedpath. Namely, if the path of movement of the finger F, predicted whenthe movement velocity and/or the movement acceleration of the finger Fis indicated by a value equal to or greater than the predetermined valueis not at the detection reference 42, it will be decided that thepredetermined non-contact operation 600 is not detected by the detectionreference 42. Then, the detection reference 42 will be changed based onthe change quantity ΔH10 having been calculated, as in the eighthembodiment.

Next, if in reference to FIG. 58 and FIG. 59, the processing executed inthe first calibration processing mode in the display device 1 achievedin variation 3 will be described. Since the processing executed in stepS764 through step S766 in the flowchart presented in FIG. 59 isidentical to that in the flowchart presented in FIG. 56, a repeatedexplanation is not provided. As the finger F moves into thepredetermined detection range 13A of the operation detector 13, as shownin FIG. 58(a), the operation detector 13 detects the movement of thefinger F as a change in the electrostatic capacitance value in stepS764. In step S765, the velocity/acceleration unit 206 calculates, basedon the detection output provided by the operation detector 13, thevelocity and the acceleration of the movement of the fingertip F. Instep S765, the operation predicting unit 211 determines whether or notthe movement velocity and the acceleration having been calculated by thevelocity/acceleration detection unit 206 are indicated by a value equalto or higher than a first predetermined value and equal to or lower thana second predetermined value. The first predetermined value is selectedin correspondence to a velocity and an acceleration at which the fingerF, moving downward from a point above the detection reference 42 ispredicted to fall short of the upper reference plane 42 a, whereas thesecond predetermined value, greater than the first predetermined value,is selected in correspondence to a velocity and an acceleration at whichthe finger F moving downward is predicted to move through the lowerreference plane 42 b. When the movement velocity and the acceleration ofthe fingertip F are indicated by a value equal to or greater than thefirst predetermined value and equal to or less than the secondpredetermined value, an affirmative decision is made in step S765 andthe operation proceeds to step S770. When the movement velocity and theacceleration of the finger F are indicated by a value either less thanthe first predetermined value or greater than the second predeterminedvalue, a negative decision is made in step S765 and the operationproceeds to step S767.

In step S767, the operation predicting unit 211 calculates a path ofmovement for the fingertip F based on the movement velocity and theacceleration calculated by the velocity/acceleration detection unit 206.In FIG. 58(b), the path of movement of the finger F calculated, i.e.,predicted, by the operation predicting unit 211 when the movementvelocity and the acceleration indicate a value less than the firstpredetermined value is indicated by a dotted line 600Ac. In step S768,the detection reference control unit 204 calculates an change quantityΔH10 for the detection reference 42 as it does in the situationdescribed in reference to FIG. 51 and changes the detection reference 42accordingly. It is to be noted that the finger reach position may bepredicted based on both the finger movement velocity and theacceleration, or based on either of them.

It is to be noted that while the calibration processing described aboveis executed in the first calibration processing mode, it may be alsoadopted in the second calibration processing mode

It is to be noted that while the operation predicting unit 211calculates a path of movement of the fingertip F in the explanationprovided above, it is not always necessary to calculate a movement path.Namely, the control unit 20 in the display device 1 does not need toinclude the operation predicting unit 211 and in such a case, thedetection reference 42 may be changed by a predetermined change quantitywhen the movement velocity and the movement acceleration calculated bythe velocity/acceleration detection unit 206 are indicated by a valueequal to or less than a predetermined value. For instance, the movementvelocity or the movement acceleration may be detected at a positionfurther up relative to the detection reference 42 by a predetermineddistance, and if the detected movement velocity or movement accelerationis equal to or lower than a predetermined value, the finger F may bepredicted to fall short of the detection reference 42 and the detectionreference 42 may be changed accordingly.

While the velocity/acceleration detection unit 206 described above readsout the electrostatic capacitance value detected by the operationdetector 13 after each time interval, calculates the velocity of thefinger movement based on the change occurring in the electrostaticcapacitance value over the predetermined time interval and calculatesthe acceleration of the finger movement based on the velocity thuscalculated, the present invention is not limited to this example and itmay be adopted in a configuration that includes an image-capturingdevice used as the velocity/acceleration detection unit 206. While thevelocity or the acceleration of the movement of the user's finger iscalculated in the explanation provided above, the velocity or theacceleration of the movement of the user's foot or elbow or a stylusheld by the user may be calculated instead.

Variation 4 of the Eighth Embodiment

At the display device achieved in the eighth embodiment and variations 1through 3 thereof described above, the position of the detectionreference 42 is changed based on the positional relationship between theposition at which the predetermined non-contact operation 600A isperformed in space and the detection reference 42 through a singlecalibration processing session. In other words, a calibration processingsession is executed in correspondence to a single user operation. At thedisplay device 1 in variation 4, a single calibration processing sessionis executed in correspondence to a user operation performed a pluralityof times. Namely, the detection reference 42 is changed based on thenumber of times the predetermined non-contact operation 600A is detectedoutside the detection reference 41 or the number of times thepredetermined non-contact operation 600A is detected at the detectionreference 42.

During a first user operation, the detection reference control unit 204determines based on the detection output provided by the operationdetector 13 as to whether or not the finger F has performed thepredetermined non-contact operation 600A, and if the predeterminednon-contact operation 600A has been detected, it further detects theposition at which the predetermined non-contact operation 600A has beenperformed in space. When the predetermined non-contact operation 600Ahas been detected at the detection reference 42, the detection referencecontrol unit 204 decides that the first calibration processing has beensuccessful and stores the decision-making results into the storage unit205. When, on the other hand, the predetermined non-contact operation600A has been detected outside the detection reference 41, the detectionreference control unit 204 decides that the first user operation hasfailed, calculates an change quantity ΔH10 as in the eighth embodimentand stores the decision-making results and the change quantity ΔH10 intothe storage unit 205. Next, decision-making results indicating successor failure of a second user operation and/or the corresponding changequantity ΔH10 are stored into the storage unit 205. The processing maybe continuously executed for a third user operation as well.

The detection reference 42 is changed based on a plurality of sets ofdecision-making results and/or the corresponding change quantities ΔH10stored into the storage unit 205 in correspondence to the user operationperformed successively over a plurality of times, as described above. Adecision as to whether or not to change the detection reference 42 basedon the decision-making results and/or the change quantities ΔH10corresponding to the plurality of user operations may be made asdescribed above through any of various methods. For instance, thedetection reference 42 may be changed if decision-making resultsindicating failure are stored successively in the storage unit 205 incorrespondence to a plurality of user operations performed successively.Specifically, the detection reference 42 may be changed if the firstuser operation and the second user operation have both been judged tohave failed. As an alternative, the detection reference 42 may bechanged if, for instance, the first user operation has been judgedsuccessful but the second user operation and the third user operationhave been judged to have failed. The detection reference 42 may bechanged if the number of operations having been judged to have failedamong the plurality of user operations is equal to or greater than apredetermined value. In more specific terms, the detection reference 42may be changed if, for instance, at least five user operations out often user operations are judged to have failed. In this case, thedetection reference 42 may be changed as soon as the user operation isjudged to have failed for the fifth time (at a time point when thecumulative decision-making results indicate five failures) or thedetection reference 42 may be changed after the user has performed theuser operation 10 times. It is to be noted that if the predeterminednon-contact operation 600A is detected outside the detection reference41 with high frequency, the frequency with which the detection reference42 is changed may be increased. Namely, assuming that a setting isselected so as to change the detection reference 42 when at least fiveuser operations out of ten user operations are judged to have failed,eight user operations out of ten may be judged to have failed. Undersuch circumstances, the detection reference 42 may be changed through asubsequent calibration session if at least three user operations out offive are judged to have failed.

The change quantity ΔH10 by which the detection reference 42 is changedbased on the results of a plurality of user operations may be calculatedthrough processing similar to that through which the detection referenceis determined in variation 2 of the first embodiment. Namely, a singlechange quantity ΔH10 may be calculated as the arithmetic mean or thegeometric mean of the change quantities calculated in correspondence tothe user operations judged to have failed. In this case, too, a newchange quantity ΔH10 may be calculated through suitable weighting, ashas been described in reference to variation 2 of the first embodiment.

It is to be noted that the detection reference 42 may be changed basedon the results of a plurality of user operations if the value calculatedas the arithmetic mean or the geometric mean of the change quantitiesΔH10 calculated in correspondence to the individual user operationsexceeds a predetermined threshold value or if the change quantities ΔH10calculated in correspondence to the individual user operations indicatea trend of increasing magnitude.

It is to be noted that while the position of the detection reference 42is changed based on the number of times the predetermined non-contactoperation 600A is detected outside the detection reference 41 in theexample described above, an operation different from the predeterminednon-contact operation 600A, i.e., part of the predetermined non-contactoperation 600A, detected outside the detection reference 41 may also beregarded as a user operation failure. Namely, the detection reference 42may be changed when part of the predetermined non-contact operation 600Ais detected successively outside the detection reference 41 as aplurality of user operations or if part of the predetermined non-contactoperation 600A is detected outside the detection reference 41 apredetermined number of times or more as a plurality of user operationsare performed.

Variation 5 of the Eighth Embodiment

The predetermined non-contact operation 600 is performed by the usermoving his finger F toward the display position 1 in the exampledescribed in reference to the eighth embodiment. This operation may beperformed by making a U-turn with the finger F, as shown in FIG. 48(a).However, the present invention is not limited to this example. Thepredetermined non-contact operation 600 may be performed by pointingthree fingers at the display position or by moving the finger F towardthe display position 1 in front of the user's body. As an alternative,the predetermined non-contact operation 600 may be performed by holdingthe finger F still for a predetermined length of time, e.g., 20 seconds.

In the embodiment described above, the detection reference control unit204 determines whether or not the predetermined non-contact operation600 has been performed based on the detection output provided by theoperation detector 13. However, the user may not always be able toperform the predetermined non-contact operation 600 accurately orcorrectly. For instance, the predetermined non-contact operation 600 mayinclude a descending movement of the finger over 10 cm immediatelyfollowed by an ascending movement of the finger over 10 cm, but the usermay actually move his finger downward over 5 cm and then move it upwardby 5 cm. The user performing the predetermined non-contact operation 600may need to point three fingers at the display position 1 but may not beable to unclench his first to point the three fingers and may end uppointing two fingers. The user performing the predetermined non-contactoperation 600 may need to move his finger F in front of his body towardsthe display position, but may move the finger F toward the displayposition at a side of his body. The user performing the predeterminednon-contact operation 600 may also need to hold his finger F still for apredetermined length of time, e.g., 20 seconds, that may move his fingerbefore the 20 second-holding time is up, e.g., after 15 seconds.

Under such circumstances, even when the central position or thedetection depth of the detection reference 42 has been changed so as toenable detection of the entire user operation at the detection reference42, the user operation will not be recognized unless the operationitself performed by the user (a detection value detected as theoperation by the user) matches the “predetermined non-contact operation600” (a reference value indicating the predetermined non-contactoperation 600). In such a case, it becomes possible to recognize theoperation by the user as the predetermined non-contact operation 600 bychanging the reference value indicating the predetermined non-contactoperation 600 as a way of changing the detection reference 42.

Namely, when a given non-contact operation performed by the user issimilar to, but not identical to, the predetermined non-contactoperation 600 or is very roughly similar, the display device 1 assumesthat the user has performed the predetermined non-contact operation 600.The display device 1 then changes (updates) the reference valueindicating the predetermined non-contact operation 600 (i.e., thedefinition of the predetermined non-contact operation 600) storedtherein by using a value indicating the operation itself performed bythe user (the detection value indicating the operation by the user). Forinstance, the detection reference control unit 204 may compare thedetection value indicating the user non-contact operation having beendetected with the reference value indicating the predeterminednon-contact operation 600 that is stored in advance. The reference valueindicating the predetermined non-contact operation 600 may be thedefinition of the predetermined non-contact operation 600 or a templateof the predetermined non-contact operation 600, stored in advance in thedisplay device 1. When the comparison results indicate that the degreeof similarity between them exceeds a predetermined threshold value, thereference value indicating the predetermined non-contact operation 600(the value stored in advance) is changed based on the detection valueindicating the user non-contact operation having been detected. Throughthese measures, the non-contact operation performed by the user isrendered effective. For instance, the reference value indicating thepredetermined non-contact operation 600 stored in advance may be a valueindicating “descent of finger F by 10 cm”. Upon detecting that thefinger F has descended by 5 cm, the reference value indicating thepredetermined non-contact operation 600 is switched to a valueindicating “descent of the finger F by 5 cm”. By changing the referencevalue indicating the predetermined non-contact operation 600 asdescribed above, a non-contact operation similar to the predeterminednon-contact operation 600 is rendered effective as well. By changing thereference value indicating the predetermined non-contact operation 600to a value that allows the user to perform the non-contact operationwith less movement, the operational onus placed on the user is reduced.

The reference value indicating the predetermined non-contact operationmay be a value indicating, “descent of the finger over 10 cm immediatelyfollowed by ascent of the finger over 10 cm “in front of the body”. Whenthe user has moved his finger downward by 10 cm and then moved thefinger upward by 10 cm at “a side of” his body, the reference valueindicating the predetermined non-contact operation 600 may be changed toa value indicating an operation defined as “descent of the finger over10 cm immediately followed by ascent of the finger over 10 cm at a sideof the body”. As a result, it becomes possible to operate the displaydevice 1 by moving the finger downward by 10 cm and then moving itupward by 10 cm at a side of the body.

It is to be noted that the detection reference 42 (the reference valueindicating the predetermined non-contact operation 600) may be changedbased on the operation by the user performed a plurality of times.Namely, the reference value indicating the predetermined non-contactoperation 600 may be changed when a non-contact operation similar to thepredetermined non-contact operation 600, though not exactly the same,has been performed a plurality of times.

As described above, the detection reference 42 may be changed bychanging the reference value indicating the predetermined non-contactoperation 600.

Variation 6 of the Eighth Embodiment

At the display device 1 achieved in the eighth embodiment and variations1 through 5 thereof the detection reference 42 is changed when, forinstance, a predetermined non-contact operation 600 or part of apredetermined non-contact operation 600 is detected outside thedetection reference 41.

As an alternative, the detection reference 42 may be changed when anoperation instructing change of the detection reference 42 is detectedby the detection reference 42. The change that may be made to thedetection reference 42 under such circumstances includes change of theposition or the expanse of the detection reference 42, and change of thereference value indicating the predetermined non-contact operation 600.In variation 6, a gesture instructing calibration, for instance, isstored in the display device 1, and the detection reference 42 ischanged when the user makes the gesture instructing the calibration atthe detection reference 42. The detection reference 42 may also bechanged in a manner similar to that described above when the gestureinstructing calibration is detected outside the detection reference 41.

Variation 7 of the Eighth Embodiment

The detection reference control unit 204 may change the detectionreference 42 in response to sound. The change that may be made to thedetection reference 42 under such circumstances, includes change of theposition or the expanse of the detection reference 42, change of thereference value indicating the predetermined non-contact operation 600and like. The display device 1 includes, for instance, a sound collector14 similar to that in variation 6 of the first embodiment and thecontrol unit 20 includes a sound detection unit 208 that detects audiodata input thereto from the sound collector 14. It is to be noted thatthe sound detection unit 208 in this variation has a speech recognitionfunction of the known art that enables it to recognize sounds other thanthe word “yes”. Upon detecting, through the speech recognition function,a speech indicating that the user “cannot perform an operation”, aspeech requesting calibration or the like, the display device 1 invariation 7 changes the detection reference 42. In more specific terms,it may move the detection reference 42 or change the expanse of thedetection reference 42 so that the position assumed by the user's fingerwhen the sound (speech) was detected is set within the section reference42. As an alternative, upon detecting the sound (speech), the detectionreference 42 may be moved toward the user by a predetermined extent,e.g., by 1 cm or the depth of the detection reference 42 may be changedtoward the user. As a yet further alternative, the reference valueindicating the predetermined non-contact operation 600 may be changed tothe detection value detected as the operation by the user at the timewhen the sound (speech) was detected. As a further alternative, thereference value indicating the predetermined non-contact operation 600may be changed by a predetermined extent upon detecting the sound(speech). For instance, assuming that the reference value indicating thepredetermined non-contact operation 600 stored in advance is a valueindicating “descent by 10 cm”, the reference value indicating thepredetermined non-contact operation 600 may be changed (updated) with avalue indicating “descent by 9 cm” upon detecting the sound (speech).

It is to be noted that it is not always necessary that the displaydevice 1 include the sound collector 14, and in such a case, the sounddetection unit 208 may detect sound by using audio data input theretofrom an external sound collector device through a wireless connection ora wired connection.

Variation 8 of the Eighth Embodiment

The detection reference control unit 204 may change the detectionreference 42 based on time. The change that may be made to the detectionreference 42 under such circumstances includes change of the position orthe expanse of the detection reference 42, and change of the referencevalue indicating the predetermined non-contact operation 600 and like.The display device 1 in variation 8 changes the detection reference 42by a predetermined extent if, for instance, the predeterminednon-contact operation 600 is not detected by the detection reference 42within a predetermined time interval. Accordingly, the control unit 20includes a time count unit and the detection reference control unit 204changes the detection reference 42 by the predetermined extent based onan output provided by the time count unit when no icon operation or thelike has been performed over the predetermined length of time after thepower switch at the display device 1 was turned on. If a subsequent iconoperation or the like is not performed after a predetermined length oftime elapses following an operation performed for a given icon or thelike, the detection reference control unit 204 changes the detectionreference 42 by the predetermined extent based on an output provided bythe time count unit having counted the predetermined length of time.

It is desirable that the detection reference 42 be moved for change bythe predetermined extent toward the user based on the time count of thepredetermined time interval in variation 8. For instance, if nooperation by the user is detected over the predetermined length of time,the central position (the overall position) of the detection reference42 may be moved toward the user or the expanse of the detectionreference 42 may be changed on the side toward the user by thepredetermined extent of, for instance, 1 cm. As an alternative, thecentral position of the detection reference 42 may be moved or theexpanse of the detection reference 42 may be changed so that theposition taken by the user's finger when the predetermined length oftime has elapsed is set in the detection reference 42. As a furtheralternative, the reference value indicating the predeterminednon-contact operation 600 may be changed to the detection value detectedas the operation by the user when the predetermined length of time haselapsed. The reference value indicating the predetermined non-contactoperation 600 may be changed by a predetermined extent once thepredetermined length of time elapses. For instance, assuming that thereference value indicating the predetermined non-contact operation 600stored in advance is a value indicating “descent by 10 cm”, thereference value indicating the predetermined non-contact operation 600may be changed (updated) with a value indicating “descent by 9 cm” oncethe predetermined length of time elapses.

Variation 9 of the Eighth Embodiment

The detection reference control unit 204 may change the detectionreference 42 based on the user's face. The change that may be made tothe detection reference 42 under such circumstances includes change ofthe position or the expanse of the detection reference 42, and change ofthe reference value indicating the predetermined non-contact operation600. The control unit 20 analyzes an image of the user's face, capturedvia, for instance, a camera installed at the display device 1 invariation 9, and upon detecting a predetermined expression on the user'sface (upon recognizing a predetermined facial expression through afunction commonly referred to as a face recognition function), thedetection reference 42 is changed. It is to be noted that thepredetermined facial expression may be that of frustration indicatingthat the user cannot perform an operation smoothly, and in such a case,the detection reference 42 is changed upon detecting a frustratedexpression on the user's face.

Upon detecting frustration in the user through the face recognitionfunction of the display device 1, the detection reference 42 may bemoved toward the user or the expanse of the detection reference 42 maybe changed so as to move toward the user by a predetermined extent(e.g., 1 cm). The detection value indicating the operation performed bythe user immediately before frustration is recognized on the user's facemay be stored and the reference value indicating the predeterminednon-contact operation 600 may be changed based on the detection valuethus stored.

Variation 10 of the Eighth Embodiment

The detection reference control unit 204 may change the detectionreference 42 (the position or the expanse of the detection reference 42or the reference value indicating a predetermined non-contact operation)when a gesture made by the user is not detected by the detectionreference 42. The user may perform a predetermined non-contact operation600 by gesturing with his hand to simulate the “stone”, the “scissors”,the “paper” or the like or by moving his finger F sideways immediatelyafter a descending movement. At the display device 1 in variation 10,characteristics information (reference values indicatingcharacteristics) for the various non-contact operations is stored inadvance in the storage unit 205. The display device 1 detects a gesturemade by the user, and determines whether or not the gesture matches anyof the predetermined non-contact operations described above by comparingthe detected gesture with a set of characteristics information selectedfrom the plurality of sets of characteristics information stored in thestorage unit 205. When the user's gesture has not been detected by thedetection reference 42, the display device 1 changes the detectionreference 42. In this situation, the detection reference 42 is changedby switching to the reference value indicating another predeterminednon-contact operation 600. Namely, the reference value initiallyselected at the display device 1 for purposes of operation detection bythe detection reference 42 may correspond to the characteristicsinformation indicating the hand gesture “stone”. In this case, if auser's gesture is not detected by the detection reference 42, thedisplay device 1 switches to the reference value corresponding to thecharacteristics information indicating an operation other than the handgesture “stone” (e.g., a specific hand gesture among the plurality ofgestures listed above, such as the hand gesture simulating the“scissors”) from the reference value for the characteristics informationindicating the hand gesture “stone”.

Variation 11 of the Eighth Embodiment

When the position of the finger F performing a predetermined non-contactoperation 600 matches a predetermined position, the predeterminedposition may be located inside the detection reference 42, outside thedetection reference 41, exactly at an icon display position, or exactlyat the border of the detection reference 42. When the predeterminedposition is located inside the detection reference 42, it is decidedthat the predetermined non-contact operation 600 has been performedwhile the finger is inside the detection reference 42. When thepredetermined position is located outside the detection reference 41, itis decided that the predetermined non-contact operation 600 has beenperformed while the finger is outside the detection reference 41. Whenthe predetermined position exactly matches an icon display position, itis decided that the predetermined non-contact operation 600 has beenperformed when the finger F is set exactly at the icon display positionin the midair image or when the finger F has performed an operation atthe icon display position. When the predetermined position is located atthe border of the detection reference 42, it is decided that thepredetermined non-contact operation 600 has been performed as the fingerF passes through a boundary of the detection reference 42 and outsidethe detection reference 41 or as the finger, having passed through theboundary, passes through the boundary again.

Variation 12 of the Eighth Embodiment

While an explanation has been given in reference to the eighthembodiment and variations 1 through 11 thereof by assuming that thedetection reference 42 achieves a depth D1 along the up/down direction,the detection reference 42 may instead be defined with a plane as is thedetection reference 40 in the first embodiment. As shown in FIGS. 60(a)and 60(b), the predetermined non-contact operation 600A performed bymaking a U-turn at a position further downward relative to the detectionreference 40 and set apart from the detection reference 40 by a distanceL1 or a distance equal to or greater than the distance L1 is detected bythe detection reference 40. The predetermined non-contact operation 600Aperformed at a position further upward relative to the detectionreference 40 (within the electrostatic capacitance detection range 13A),as shown in FIG. 61(a), is detected outside the detection reference 41by the operation detector 13, whereas part of the predeterminednon-contact operation 600A performed by the finger passing through thedetection reference 40, as shown in FIG. 61(b) is detected outside thedetection reference 41 by the operation detector 13. In the situationsillustrated in FIGS. 61(a) and 61(b), the position of the detectionreference 40 (the position taken along the Z direction in FIG. 61) maybe changed by change quantity ΔH10 calculated based on the distance fromthe detection reference 40.

The processing described in reference to the eighth embodiment andvariations 1 through 12 thereof may be also executed at the displaydevice 100 achieved in any of the fourth embodiment, variation 1 thereofand the seventh embodiment.

While the predetermined non-contact operation 600 is performed withregard to the display position of the midair image in the eighthembodiment and variations 1 through 12 thereof described above, thepresent invention is not limited to this example. The position of thedetection reference 42 may be changed based on the positionalrelationship between the position at which the predetermined non-contactoperation 600 is performed in space and the detection reference 42 when,for instance, the predetermined non-contact operation 600 is performedin space with regard to an image displayed at the display unit 11 of thedisplay device achieved in any of the eighth embodiment and variations 1through 12 thereof.

It is to be noted that while the display device 1 in the eighthembodiment and variations 1 through 12 thereof includes at least thecontrol unit 20, the display unit 11 and the operation detector 13, thepresent invention may instead be adopted in a control device configuredwith the control unit 20 alone or a control device configured with thecontrol unit 20 and the operation detector 13. The control unit 20 mayinclude at least the calibration unit 203 and the detection referencecontrol unit 204.

In the various embodiments and variations thereof described above, amidair image is generated via the image forming optical system 12 incorrespondence to an image displayed at the display unit 11 in thedisplay device 1. A midair image is generated via the image formingoptical system 112 in correspondence to an image displayed at thedisplay unit 111 at the display device 100. However, a midair image maybe generated by adopting a structure other than those described abovethrough the following methods. The structures explained below simplyrepresent examples and a midair image may be generated by assuming astructure other than those described below.

A midair image may be generated at a display device by displaying animage to be viewed with the right eye and an image to be viewed with theleft eye, which manifests parallax relative to the image to be viewedwith the right eye, on display at the display unit so as to create animage perceived by the user to have depth, unlike the images displayedat the display unit. This method creates a user perception that animage, corresponding to the images displayed at the display unit, is ondisplay in midair.

The user may wear a display device configured with a transmissivehead-mounted display (HMD). An image displayed at the HMD issuperimposed over the actual visual field and thus the user feels as ifthe image displayed at the HMD is floating in midair.

It is to be noted that a midair image may be generated by projecting avirtual image or by directly forming an image in the user's retina. Inyet another midair image generation method, light may be emitted in midair by condensing laser light in midair and forming plasma with airmolecules. Through this method, a three-dimensional image is generatedas a real image in midair by controlling the laser light condensingposition at any desired position in the three-dimensional space. In yetanother midair image generation method, an image may be generated inmidair via a display device having a function of creating fog in the airand a projector function by creating a screen with the fog in the airand projecting an image onto the screen formed with the fog (fogdisplay).

A program enabling calibration at the display device 1 or 100 may berecorded into a computer-readable recording medium, and the calibrationmay be executed based on the program read into a computer system. It isto be noted that the “computer system” in this context may include an OS(operating system) and hardware such as peripheral devices.

It is to be also noted that the “computer system” may include a homepageprovider environment (or a display environment) achieved in conjunctionwith the WWW system. The “computer-readable recording medium” may be anon-volatile writable memory such as a flexible disk, a magneto-opticaldisk, a ROM and a flash memory, a portable medium such as a CD-ROM or astorage device such as a hard disk built into a computer system. The“computer-readable recording medium” may be a storage medium capable ofholding a program over a specific length of time, such as a volatilememory, e.g., DRAM (dynamic random access memory) in a computer systemfunctioning as a server or a client when the program is transmitted viaa communication network such as the Internet or via a communication linesuch as a telephone line.

The program stored in a storage device or the like in a computer systemmay be transmitted to another computer system via a transmission mediumor on a transmission wave in the transmission medium. The “transmissionmedium” through which the program is transmitted in this context refersto a medium having a function of information transmission, examples ofwhich include a network (communication network) such as the Internet anda communication line such as a telephone line. The program describedabove may enable some of the functions described earlier. The programmay be a differential file (differential program) that works inconjunction with a program already recorded in the computer system so asto enable the functions described earlier.

It is to be noted that a detection device that detects an operation by auser on a midair display, comprising a detection unit that detects apredetermined non-contact operation by a detection reference and acontrol unit that changes a positional relationship between thedetection reference used for operation detection and the display, andchanges the detection reference when the predetermined non-contactoperation is not detected by the detection reference, with the controlunit being capable of changing the positional relationship for eachuser, may be configured by combining any of the various embodiments andnumerous variations thereof described above. The control unit in thedetection device may change the detection reference based on sound. Thecontrol unit in the detection device may also change the detectionreference based on time. The control unit in the detection device maychange the detection reference based on the user's face. The controlunit in the detection device may change the detection reference when aspecific movement is not detected as the predetermined non-contactoperation by the detection reference. The control unit in the detectiondevice may change the detection reference when a “press down” operationis not detected as a predetermined non-contact operation by thedetection reference. The control unit in the detection device may changethe detection reference when a gesture is not detected as apredetermined non-contact operation by the detection reference. Thecontrol unit in the detection device may change the detection referencewhen the shape of an operating object performing the predeterminednon-contact operation does not match a predetermined shape. A detectiondevice that detects an operation by a user on a midair display,comprising a detection unit that includes a detection reference used fordetection of a non-contact operation and a control unit that changes apositional relationship between the detection reference used fordetecting the non-contact operation and the display, and changes thedetection reference based on the non-contact operation detected outsidea detection reference, with the control unit being capable of changingthe positional relationship for each user, may be configured bycombining any of the various embodiments and numerous variationsdescribed above.

It is to be noted that a detection device comprising a detection unitthat detects a predetermined non-contact operation by a detectionreference and a control unit that changes the detection reference whenthe predetermined non-contact operation is not detected by the detectionreference, with the control unit being capable of changing a positionalrelationship based on an operation by a user, may be configured bycombining any of the various embodiments and numerous variations thereofdescribed above. A detection device comprising a detection unit thatdetects a predetermined non-contact operation by a detection referenceand a control unit that changes the detection reference when thepredetermined non-contact operation is not detected by the detectionreference with the control unit being capable of changing a positionalrelationship based on user information, may be configured by combiningany of the various embodiments and numerous variations described above.A detection device comprising a detection unit that detects apredetermined non-contact operation by a detection reference and acontrol unit that changes the detection reference when the predeterminednon-contact operation is not detected by the detection reference, withthe control unit being capable of changing a positional relationshipbased on a change in an environment surrounding the detection deviceattributable to a user, may be configured by combining any of thevarious embodiments and numerous variations described above.

It is to be noted that a detection device that detects an operation by auser on a midair display comprising a detection unit that detects apredetermined non-contact operation by a detection reference and acontrol unit that changes the detection reference when the predeterminednon-contact operation is not detected by the detection reference, withthe control unit being capable of changing a positional relationship bycontrolling the display, may be configured by combining any of thevarious embodiments and numerous variations described above.

It is to be noted that a control device comprising a control unit thatchanges a positional relationship between a detection device capable ofdetecting an operation by a user on a midair display and the display bycontrolling the display based on the operation by the user, with thecontrol unit being capable of changing the positional relationship foreach user, may be configured by combining any of the various embodimentsand variations thereof described above. A control device comprising acontrol unit that changes a positional relationship between a detectiondevice capable of detecting an operation by the user on a midair displayand the display by controlling the display based on the operation by theuser, with the control unit being capable of changing the positionalrelationship for each user, may be configured by combining any of thevarious embodiments and variations thereof described above. A controldevice comprising a control unit that changes a positional relationshipbetween a detection device capable of detecting an operation by a userperformed on a midair display and the display by controlling the displaybased on a change in an environment surrounding the detection deviceattributable to a user, with the control unit being capable of changingthe positional relationship for each user, may be configured bycombining any of the various embodiments and variations thereofdescribed above.

It is to be noted that a control device comprising a detection unit thatdetects a predetermined non-contact operation by a detection referenceand a control unit that changes a positional relationship between thedetection reference used for detecting an operation by a user on amidair display and the display by controlling the display and changesthe detection reference when the predetermined non-contact operation isnot detected by the detection reference, with the control unit beingcapable of changing a positional relationship for each user, may beconfigured by combining any of the various embodiments and numerousvariations thereof described above. The control unit in the controldevice may change the detection reference based on sound. The controlunit in the control device may change the detection reference based ontime. The control unit in the control device may change the detectionreference based on the user's face. The control unit in the controldevice may change the detection reference when a specific movement isnot detected as the predetermined non-contact operation by the detectionreference. The control unit in the control device may change thedetection reference when a press down operation is not detected as thepredetermined non-contact operation by the detection reference. Thecontrol unit in the control device may change the detection referencewhen a gesture is not detected as the predetermined non-contactoperation by the detection reference. The control unit in the controldevice may change the detection reference when the shape of an operatingobject performing the non-contact operation does not match apredetermined shape. A control device comprising a detection unit thatincludes a detection reference used for detecting a non-contactoperation and a control unit that changes a positional relationshipbetween the detection reference used for detecting a user performed on amidair display and the display by controlling the display and changesthe detection reference based on the non-contact operation detectedoutside a detection reference, with the control unit being capable ofchanging the positional relationship for each user, may be configured bycombining any of the various embodiments and numerous variationsdescribed above.

As long as the features characterizing the present invention are notcompromised, the present invention is in no way limited to theparticulars of the embodiments and variations thereof described aboveand other modes or combinations that are conceivable within thetechnical teaching of the present invention are also within the scope ofthe invention.

REFERENCE SIGNS LIST

-   1, 100 display device-   11, 111 display unit-   112 image forming optical system-   13, 113 operation detector-   14 sound collector-   18, 118 image-capturing device-   19 environment detection unit-   20 control unit-   116 light emitting element-   117 light receiving element-   119 actuator-   201 image generation unit-   202 display control unit-   203 calibration unit-   204 detection reference control unit-   205 storage unit-   206 velocity/acceleration detection unit-   207 stop position predicting unit-   208 sound detection unit-   209 image analysis unit-   210 user information analysis unit-   220 display position control unit-   500 display position change unit

1-47. (canceled)
 48. A detection device that detects an operation by auser for a midair display, the device comprising: a control unit that isconstituted by a processor and that changes a positional relationshipbetween a detection reference at which the operation is detected and themidair display, wherein the control unit is capable of changing thepositional relationship based on the user.
 49. The detection deviceaccording to claim 48, wherein the control unit changes the positionalrelationship between the detection reference and the midair display bycontrolling the detection reference based on the operation.
 50. Thedetection device according to claim 49, wherein the control unit changesthe positional relationship by changing a position of the detectionreference.
 51. The detection device according to claim 50, wherein thecontrol unit controls the position of the detection reference based on adirection of the operation for the midair display.
 52. The detectiondevice according to claim 49, further comprising: an obtaining unit thatobtains a position at which the operation is detected by a detectionunit that detects the operation at the detection reference or outsidethe detection reference, wherein the control unit controls a directionto move the detection reference based on whether or not the position ofthe operation detected by the detection unit reaches the detectionreference.
 53. The detection device according to claim 52, wherein: theoperation is a press down operation for the midair display; and thecontrol unit moves the detection reference in a direction of the pressdown operation or in a direction opposite to the direction of the pressdown operation.
 54. The detection device according to claim 53, whereinthe position of the operation detected by the detection unit is aposition based on a reach position of the press down operation or adesignated position by the user.
 55. The detection device according toclaim 53, wherein the control unit moves the detection reference in thedirection opposite to the direction of the press down operation when theposition of the operation detected by the detection unit reaches thedetection reference.
 56. The detection device according to claim 53,wherein the position of the operation detected by the detection unit isa position based on a reach position of the press down operation or adesignated position.
 57. The detection device according to claim 49,wherein the control unit controls a part of the detection reference. 58.The detection device according to claim 57, wherein: the midair displayincludes a first midair display and a second midair display; and thedetection reference includes a first detection reference that detectsthe operation for the first midair display and a second detectionreference that detects the operation for the second midair display. 59.The detection device according to claim 58, wherein the control unitsets the first detection reference and the second detection reference atdifferent positions.
 60. The detection device according to claim 49,wherein the control unit changes the positional relationship by settinga size of the detection reference along a direction of the operation.61. The detection device according to claim 60, wherein the control unitcontrols the size of the detection reference along the direction of theoperation based on a quantity of the operation.
 62. The detection deviceaccording to claim 48, further comprising: a setting unit that sets thedetection reference, wherein the control unit changes the positionalrelationship between the detection reference set by the setting unit andthe midair display.
 63. The detection device according to claim 48,further comprising: a storage unit that stores the detection reference.64. The detection device according to claim 48, wherein the control unitchanges the positional relationship based on the operation by the user.65. The detection device according to claim 64, wherein the control unitchanges the positional relationship so as to set the detection referenceover a predetermined range that includes a reach position of a pressdown operation for the midair display by the user.
 66. The detectiondevice according to claim 65, wherein the control unit sets thedetection reference over a three dimensional area between (i) a positionset apart from the reach position by a predetermined distance along adirection opposite from a direction in which the press down operation isperformed and (ii) the reach position.
 67. The detection deviceaccording to claim 65, wherein the control unit determines the reachposition for the press down operation based on a velocity or anacceleration of the press down operation by the user.
 68. The detectiondevice according to claim 48, wherein the control unit changes thepositional relationship based on a designated position designated by theuser.
 69. The detection device according to claim 68, wherein: theoperation by the user is performed with a finger of the user; and thecontrol unit designates a detected position of the finger as thedesignated position when a sound from the user is detected.
 70. Thedetection device according to claim 64, wherein the control unit changesthe positional relationship based on a plurality of operations performedby the user.
 71. The detection device according to claim 48, furthercomprising: a detection unit that detects the operation at the detectionreference or outside the detection reference.
 72. The detection deviceaccording to claim 71, further comprising: an image-capturing unit thatcaptures an image of the operation by the user, wherein the detectionunit detects the operation by the user based on the image captured bythe image-capturing unit.
 73. The detection device according to claim48, further comprising: a display unit that displays the midair display.74. An electronic apparatus equipped with the detection device accordingto claim
 48. 75. A detection method for detecting an operation by a userfor a midair display, the method comprising: changing, by the user, apositional relationship between a detection reference at which theoperation is detected and the midair display.
 76. The detection methodaccording to claim 75, wherein changing the positional relationshipbetween the detection reference and the midair display is performed bycontrolling the detection reference based on the operation.